I do MO- I can still remember my mom buying them to pay bills with; she would mail both the business check and a MO for the personal account at the same time. I've even used them a few times, too. A lot of people wtill use them to pay bills with, and a lot of older poeple use them becayuse they feel it's better than cash. As with checks, wait till you recieve the money order and then take it to Wal-Mart or the bank to cash it.
Honestly, I doubt somebody is going to go through all teh trouble of sending a mo to scam you out of $20 worth of merchandise. Now, $100? That I might think differently about.