There are lots of honest, hard-working, quality-conscious contractors out there. But mixed in with them are the unscrupulous guys - either contractors who don't care how the job turns out as long as they collect your money, or the outright con artists who use the construction game as another way to a fast-and-easy payday. Either way, it's your cash they'll be walking away with. And your toilet will still leak.

One common trick is the building supply bait-and-switch. Let's say Jim's Building Company gives you an outstanding deal on a new storm door and matching storm windows. You agree to the amazing low price and sign on the dotted line. Jim starts the work in a few days but there's a problem. The supplies he normally uses are out of stock and it could take months to get more in. He'd be happy to wait, but the doors and windows have already been removed and it's late November. So, Jim's really sorry, but he's going to have to use slightly more expensive supplies to finish the job. "Slightly more expensive" can easily mean double the cost. Or Jim might not even take the blame himself. He may blame your house, claim it's an odd design, so the replacement parts have to be custom fit. Custom fitting is expensive. If you try to cancel, he'll tell you it's too late - the parts are already ordered. Meanwhile, the November wind is blowing through your house and you have to chip the ice off the toilet to use it.

Far more common, however, is good old fashioned slipshod work. This crooked contractor will rush through the job - in some cases, barely do the work at all - and demand payment. An experienced crook in this field will know how to apply "icing" to the surface of the job to make it look like good craftsmanship, but this "icing" will wear off quickly as the actual work shows through. By that time, the crook is long gone. But the experienced crooked contractor is usually prepared in the event that the home owner notices the shoddy workmanship halfway through the job. They'll often sneak in an extra page into the pile of papers you signed when you hired him, one that says, in essence, that you agree that the work has been completed to your satisfaction. Your signature on that page makes it much more difficult to fight.

Another scam is the lien trick. This is where contractors include a special clause in their contracts: If you don't pay, the contractor reserves the right to place a lien on your property. And that pretty much means that you'll run into trouble down the road when you try to sell the place, or even foreclosure. So in this case if you see the ripples in the drywall or the trim that's already starting to fall off and you refuse to complete payment, he has the upper hand. Technically, a contractor is allowed by law to place a lien on property if he is not paid. Honest contractors will do this only as a last resort.

Michael Russell Your Independent guide to Fraud.