Something, I've learned in my time as a Pro in Las Vegas is that
there are bad players at all limits.
I know it sounds hard to believe, but yes there are even bad players playing 4000-8000 with Doyle, Phil Ivey and all the other famous top pros. Why do you think they play?

Rich people, CEO's of big companies, and business owners want to play against the best players (mostly for ego) and want to play for stakes that mean something to them. Money and Limits is all relative to your bankroll and income level.
I think what you will find is that the higher limits you play, the better players do play a lot better, but the bad players play just as bad as the donkeys playing 3-6 Hold'em.
I personally don't see much difference between online and live play regarding the donkey factor, other than what I mentioned above about the good players playing extremely well.
just my two pesos, curious as to others experiences as well.
Jason