Yep, they do. stories abound of under-spec units, (both power and mode type) complete failures, and all that jazz.
I've personally tested 6 WL's, and only one of them - a P125 - performed in-spec. The others were 2 35mW pens, a Core, 2 Elite 150's (Those were the ones sent to the winner of the Instructables contest - it had to be RMA'd, and the 2nd unit was still defective).
Absurd pricing, high failure/underspec rate. I got lucky, the only thing I ever ordered from them, a Pulsar 100, is still going strong after two years, overspec at about 125mw.
Many better companies to deal with these days. Nova, Lucent, Laserglow, Optotronics, etc.