Yup, when you bet people put you on a made hand. In position my favorite thing to do is actually re-raise a non paired board with flush draw. For a few reasons:

1) If your opponent simply calls then he's very likely to put you on a made hand that has him worried, or he might outright fold. This completely conceals your hand or lets you win a pot right there. There's a good chunk of players will lay down TPTK to a re-raise on the flop.

2) Unless the turn gives him a hand that's dripping with dollar signs most players will check to the raiser. If there's more than two handed and your opponent is smartly betting pot odds this means you'll get to see the river cheaper than you would have if you don't hit on the turn or it justifies a bet on the turn if you do hit it.

3) If your opponent continues to raise on the turn after simply calling that gives you a hell of a lot of information. The turn helped him, if the board paired with the turn then its time to get worried, if a paint straight hit then I might make the laydown there too.

4) Rarely you may get a cowboy that think he's going to represent the flush if you hit on the turn, because he's assuming you have a made hand and are going to be scared off by it. This... this is priceless.

Anyone of these are not enough to re-raise, but all four together are a pretty damn good reason to re-raise in position. Out of position... hell no, don't even think about it.

Out of position, such as UTG, I'm very likely to put in a nice 1/3 to 1/2 of pot bet depending on how the board hits if I get re-raised then I'm likely to lay it down.