I've got a fake cashiers check for $4500 and a fake certified check for $7500 staring me in the face right now. One is on check stock, from a California credit union with watermark check paper, but the printer couldn't do the signature line microprinting. The other, ostensibly from the American Express Bank is on plain paper and the watermark is visible on the reverse but very smudged looking. A better printer as the microprinting doesn't look too bad.
Both came from Nigerian scam attempts to buy a shotgun. They used telephone and emails with the true origins blocked and fake ones substituted. I suspected there was a scam when both checks arrived in express envelopes from US addresses, neither of which had any relationship to the location of the person who supposedly wanted to buy the gun. Both turned out to have been fowarded from mailing services. Then when I checked the email routing none of them were consistent with ISPs anywhere near the purchasers, and one popped up as being from Lagos, Nigeria. I guess they got sloppy.
According to the American Express agent I phoned their fake certified checks turned up all over the world. One attempt to cash one was only 2 blocks from her office!
Apparently the credit union has much bigger problems as it exists and I tried to call it, but the lines were always busy.
This scam is so common that the police weren't even interested. I'd guess a USPS counterfeit money order might get some attention from the postal inspectors but maybe that's just wishful thinking.