One thing that I'm constantly seeing at lower limits NL tables are people incapable of protecting their flopped two pair.
I guess they're not incapable of doing that, they just choose to do it in the hopes of sugar plum fairies on the next two streets.
I think it was Phil Gordon who said that two pair is the average holding in hold'em.
The hand simply has to be protected. Doyle Brunson once said it's good to play two pair fast.
And what's worse, people are slowplaying it and even taking it to the river when the board pairs it is obvious their hand could be counterfeited.