my personal rule of thumb : if they're going for the eccentricity, it's absurd -- but if they just act that way and they lean-in they're weird.

Tim & Eric and similar acts are absurd -- the people themselves are somewhat normal and put on a show when the gong sounds; this is obvious in their 'normal' productions.

Bjork, Steven Wright, Emo Phillips, Andy Kaufman, Tom Waits -- they roll out of bed 'acting that way'.