Pop culture and some instances of real life have trained us to think serial killers are driven, meticulous etc. and I don't know how much of this is dramatised, presumably a lot, but he seems like a fecking idiot. Albeit an evil fecking idiot. Astonishing how he got away with as much as he did.
Like the smell of rotting flesh in the basement; "Eh, yeah. Dead raccoon. Can't get to it. The smell will go away." It makes the people around him who are unknowingly complicit look idiotic and never mind the police who seem to be doing feck all about all these missing men but given the victims are gay men and gay minorities in that time period, that isn't surprising.