scam

scam (a clever but dishonest plan to cheat people) — жульничество, надувательство, махинации, авантюра

Example: Don't part with any money to NNN. It's just one big scam. — Не вкладывай ничегов NNN. Это сплошная авантюра/жульничество.

Example 2: These kinds of credit repair clinics are often scams. They can do exactly what you can do yourself.

Example 3: With respect to computers, many of the advantages have spawned a nightmarish array of problems. While technology has now given us the ability to shop from home, it has opened a whole new frontier in which con artists can conduct scams – a frontier that authorities admit is impossible to police. While it has enabled us to bank by mail, it has brought on a wave of identity theft such as we have never before seen.

Related vocabulary:
[развод на бабки]
[лохотрон]
a con artist