I muck all of those.

Hand 1) I check/fold the turn. Not worth the $5 (I'll use a dollar sign)

Hand 2) I think the easiest laydown. The turn brought both the flush and the one-card straight with a jack. I think he's got a flush.

Hand 3) I think Fnord would say "you have to call that sometimes." I say fold it this time. I don't usually pay off when people hit the flush. If they're bluffing, okay, they drew without odds to TRY and bluff me. If they make a smaller raise I probably call.

Hand 4) I think the first 10.50 was put in behind. If he doesn't have a flush, he's surely at least got you kicked. I think he has a flush. Easy river fold.

I've been playing 100NL lately, and I don't feel like (most) of the players are big bluffers. They overestimate hand strength a lot (I'm one of those), but raises in a medium sized pot are usually pretty big raises. I wouldn't expect you to win any of the above hands if you called.