Given that it happened several times with several vendors, I suspect there's a systematic problem due to incentives - higher power bulbs command higher prices, and most buyers don't have the test equipment needed to detect the fraud; and even when someone does detect the fraud you just have to refund them and claim it was an accident.

Needless to say, if the conditions of the market mean that fraudsters out-compete honest sellers, all the honest sellers have to quit or resort to fraud, and the market becomes useless to consumers.