I used to know some people who playtested for GW about 15 years ago. The trouble then, they said, wasn't that GW didn't playtest, but that they didn't listen to what the playtesters told them. Apparently, if their assessments are correct, there was a great deal of confirmation bias.
Dark Eldar plog: Drug-Crazed Space Elves
Stupid humans plog: Calyptra's Stupid Humans
Vampire Counts plog: Bat Country