Due credit to actor Jake Torpey in this video for doing a spot-on impersonation - most people who do Wiseau, just like people who do Schwarzenegger, think that "Generic Foreign Accent #32.5" is sufficient (sorry, Patton Oswalt, but you are one of the major offenders here). No. You have to think about everything, or the voice you chose will trick you, will betray you, and you are the fool.
Although if Torpey were truly method about it, he'd have weirdly scarred his body and done some nude scenes. Holy Repetitive Candles, Batman!
h/t Gallen_Dugall, who did not get the references but knew that I would.