Talk about the hidden horrors of homebuying.

Real estate broker Nick Rioux remembers several eager buyers calling about the ads for a charming house in an upscale Worcester neighborhood.

Yet, one grisly nugget wasn't included in those ads.

One October night in 1992, a Clark University genetics professor was bludgeoned with a baseball bat and strangled with a stereo wire when she returned to the Uncatena Avenue home and interrupted a neighbor rifling the place.

"The listing broker didn't tell us," said Rioux, who discovered the gruesome history and told clients. "They shuddered and said 'No thank you,' and, 'That's creepy, I don't want to get near it.' "

Between fears of lingering, bad karma and concerns about the property's resale value, clients stayed away in droves. Rioux said the house eventually sold -- a year later and for substantially less than the market value.

Come Nov. 9, it's going to become harder to unearth the dirt on your potential new home. A new state law will protect brokers and sellers from lawsuits for failing to tell a buyer about a murder, rape, suicide or other crime that occurred on the property. Ditto for reported ghost sightings.

Consumer advocates say that new law, coupled with state licensing rules that require few broker's disclosures, means buyers are pretty much on their own discovering a home's hidden horrors.

"Sellers or agents can't go out of their way to tell you something that's not true -- they can't lie," said Anne Collins, deputy director for enforcement at the state's Division of Registration, which monitors the real estate industry. "But if they're silent about something, they're probably within their rights."

Despite last week's upward spike, mortgage rates are still low and are expected to push the summer's homebuying well into the fall. In the rush to buy and get settled before the holidays, consumer advocates remind shoppers to scrutinize potential pitfalls where they usually forget to look -- outside a property's four corners.

For instance, have the streets in the new housing development you're eyeing been accepted by the town? If not, homeowners in the development could end up footing major bills for roadway construction and maintenance.

What about the luscious, empty field nearby? Is that about to morph into a crowded new housing development?

The Massachusetts Association of Realtors says it's not fair for buyers to assume brokers know such detailed information. That's one of the reasons, it says, it pushed for the new, so-called "stigma law" that protects brokers from failing to mention things like a property's dark past. The MAR says the law also protects the privacy of sellers, because it includes a clause about not disclosing whether a previous owner or occupant had HIV or AIDS.

"The law is not about homes, it's about the people who lived in those homes and their right to privacy," said the MAR's general counsel, Stephen Ryan. "There was a need to have a bright line for clarification about what is material and what is immaterial in home sales."

With the new law, Massachusetts joins 29 other states with similar legislation, according to Ralph Holmen, general counsel for the National Association of Realtors. Yet, he said, many of those states have something Massachusetts does not: a law requiring sellers to tell buyers about other potential problems -- everything from water in the basement to leaks in the roof.

It's the lack of such disclosure requirements in Massachusetts that prompted Nick Rioux to switch alliances. He's the Shrewsbury broker who alerted clients about the grisly Worcester murder. In 1990, he went from selling homes for clients to exploring a home's potential problems for buyers.

Today, he is vice president of the Buyer's Network, the 100-member trade association of Massachusetts brokers and agents who only represent buyers.

Rioux said many homebuyers -- and the home inspectors they hire -- are so focused on structural problems in the house they forget to consider outside issues.

Rioux and other buyer brokers urge clients to go back to the neighborhood at a different time of day than when they were shown the house.

"Drive around the neighborhood. Walk the area. Listen for a railroad," Rioux tells clients. "You'll be surprised what you can hear. There's highway noise. I tell them to put a picture of themselves on the back deck reading the paper on Sunday morning. Could you read the paper there with that noise? That has prevented a lot of people from buying."

Canton-based broker Bob Simone, president of Buyer's Network, advises clients to get a certified plan from sellers showing the property's boundaries -- before signing the purchase and sale agreement.

Simone painfully recalls a client from Marlboro who discovered at closing that the 35,000-square-foot dream property he thought he was buying -- including an elaborate sprinkler system and barn with electricity -- was only 20,000 square feet, and all the good stuff was on his neighbor's property.

"At least twice a year, we find plot-plan defects or errors in the representation of the property's visual boundary," Simone said. "Most of this is not malicious misrepresentation, it's just human error."

Even the town's maps and tax records had the wrong information, Simone said, explaining why he advises clients not to rely on those for boundary lines.

Less dramatic, but plenty costly, is the story from Wendy Rivera, 28, and her fiancé, Fernando Garcia, 30.

Just days before the couple's August closing on their first home, a fixer-upper in affordable Clinton, the mortgage company called with some budget-busting news. A search revealed a quiet, nearby brook, which put the house in a flood zone, tripling the homeowner's insurance.

Turns out, even the couple's buyer's broker missed the brook. It's shrouded by trees, three doors away, across a street and down a steep embankment.

"We're going to have to work a little harder," said Rivera, a home health aide, who, along with her fiancé, works nights cleaning offices, to make ends meet.

Staffers at the Boston-based Toxics Action Center offer still more caveats -- enough to give even seasoned homebuyers palpitations. The nonprofit helps consumers research contamination in their neighborhoods.

Right now, it's working with a group of Stoughton residents who discovered toxic chemicals from some nearby industries seeping into the air of four homes. Those residents are afraid the pollution is creeping toward more homes.

Chris Goffredo, 28, said his family was leery of buying into the neighborhood seven years ago, after noticing a couple of companies abutting the wetlands near their property.

"We checked in town hall to see what kinds of companies they were. We were told by the environmental officer for the town that it was fine, that there was nothing to worry about," Goffredo said, adding that he's developed seizures and liver problems he believes are linked to chemicals from those companies.

Turns out, state environmental officials had been monitoring chemical releases from one of the nearby companies when the Goffredos moved in. Now, a new state environmental report indicates the Goffredo family and one other household are facing "imminent hazard" from exposure to leaking chemicals.

Saying that kind of homeowner nightmare is more common than many realize, Toxics Action Center director Matthew Wilson advises homebuyers to check state Department of Environmental Protection files for the location and history of nearby industries, gas stations and even closed landfills that could be leaking contamination.

But, he said, even those records can be incomplete.

"I advise people to really take a tour of the neighborhood. Talk to neighbors," Wilson said. "A lot of times we have found contamination in the middle of the woods, where (companies) might have dumped stuff. It's really random."

Those who monitor the state's 127,000 licensed real estate agents say most are diligent and err on the side of disclosing to buyers potential red flags. The catch is, sometimes sellers aren't honest with their brokers about problems, said Joseph Autilio, legal counsel for the state's Board of Real Estate Brokers and Salesmen.

"It might not be reasonable to expect a broker to have the information," Autilio said.

Advice for homebuyers?

"Don't assume anything. The bottom line is, to be safe, ask questions," said Anne Collins, of the state's Division of Registration, which investigates reports of bad brokering.

Collins also suggests buyers make sure the seller or agent puts the answers in writing.

"If there is a problem later on," she said, "you want to be able to prove it."