Updated on June 29, 2009.

TODAY, CONVICTED PONZI-SCHEME PERPETRATOR Bernard Madoff is expected to learn his fate at a sentencing hearing in a Manhattan federal court. Ever since the fraud, which bilked thousands of investors for tens of billions of dollars, was exposed, there s been no shortage of scolds willing to point out the red flags -- obvious in retrospect. But an investment scam -- or a cheating broker -- is a lot harder to spot in the moment. "Upfront, it s so hard to tell," says Harry Miller, who runs the securities litigation practice at Burns and Levinson in Boston.

Here are five signals to dig deeper before investing:

Outta sight returns: Other than a CD or a bond held to maturity, there s no investment on the market that guarantees a steady return. And there s no investment that only goes up. Anyone promising a consistent, high rate of return, year in and year out, isn t giving you the full story.

Vague on the details: Anyone managing your money should be willing to explain exactly what investments she s buying and why -- in language you can understand. A lot of investment professionals retreat to jargon, which doesn t necessarily make them cheaters, but if your request for details in plain English isn t respected, that s a bad sign.

Mind games: When the Consumer Fraud Research Group listened to hundreds of tapes of scam artists pitching investments, they found that the psychological push was strong. Watch out for sales people who promise exclusivity -- "not everyone can get this product, you know" -- or scarcity -- "and it won t be available forever." While all sales tactics have an element of pressure or persuasion, no reputable advisor should object to you taking time to think through your options.

Missing documents: Every stock and mutual fund has a prospectus; every bond has an offering circular. In spite of so much advice to the contrary, few people ever read these documents. Fine. They should at least exist, and your broker should be willing and able to make them available before he takes your money. Furthermore, says Miller, your monthly statements should reflect the name of a recognized brokerage that s protected by the Securities Investor Protection Corporation. Not sure? Call the SIPC or your state securities regulator to make sure the firm's legit.

You know it in your gut: Many Madoff investors acknowledged they suspected he wasn t doing what he said he was. They just didn t think he was stealing. And the returns were too good to walk away. In fact, most investment fraudsters tip their hands in one way or another -- or in several.

They re counting on investors to be greedy enough to quash any reservations.

Need a second opinion? The Financial Industry Regulatory Authority built a Scam Meter to tell you just how many red flags that sure thing raises.