Online I play full ring Limit and I've been wondering the same thing, when I get on a loose table. This becomes especially true when you know something about the players at the table. For instance, I was at a table like this yesterday.....
Party .50/$1 Limit
2 rocks
1 T-AA
5calling stations/fish etc
1 maniac/LA-A
Folded to me in middle postion, I look down at AQo. Now for me, on a tighter table, I'd raise without a doubt here, however, I know that almost everyone behind me is going to call, not matter what I do. They don't notice or care that I had a V$IP of 18%. Sooo, if I miss my flop, I'm screwed. If 5-6 of them see the flop, 3-5 of them will see the river with any two cards. Any continuation bets by me will be called. If the maniac hits any part of the flop he's re-raising me, so a bet by me is almost silly unless the flop hit me good or I picked up a good draw.
To me this is where I start falling apart. When playing with a rock garden it's very hard to get paid for your big hands. But at least you know your bets are more often respected. With calling stations, fish, maniacs, I know that if the flop comes 2810 rainbow, someone probably hit something better than my AQo because these morons called with junk.
It is very frustrating when raises aren't respected, so to the OP, I know what you mean. It might be the wrong theory but I often wait until I have a really big hand and hope I can hit something. Marginal hands that I might raise on a tighter table such as K10, 910s, A10 etc, I will just call with because I can get away from them cheaply if I miss the flop. On a tighter table a continuation bet will often run others out of the pot and at least get you a free river card if you wanted.