Long Post.....
It happens Weekendalki...BUT there are 30k plus players playing on the site right now probably 16k of which are playing for money. The likelihood of you being at a table where there is collusion is slim.
I play there frequently and I would say that over 80%
of the time I sit at a table, I have never played with AT LEAST 6-7 of the players. That is at the middle/higher limits where there are fewer games and the same folks tend to play them. If you play lower limits you shouldn't be too concerned. (Would a group of guys who wanted to cheat really do it at a 3/6 or 2/4 game?....If you think so you should NEVER play online.)
I've played there (or Empire Poker) for OVER a year and logged an unmentionable amount of hours and I've seen and reported collusion twice and suspected it maybe two or three other times. Trust me that's not a lot and I look for these things.
I think what happens more than the type of collusion that you mention is soft playing. Your post isn't specific or even details what you mean by "f.ck the poor sap" but I do suspect that there is a decent amount of guys that IM each other their hands and decide to fold early b/c their buddy has them beat. That should affect your EV very little.
BTW, ALL the poker sites employ collusion detection software. Not sure how useful it is but it's used.
If you don't live near a cardroom then this is the next best thing, play without fear. If you do or decide to play here is some unsolicited advice:
1) There are people making money playing online poker.
2) There are people who earn their living playing online poker.
3) Some of the guys you see on TV during the WSOP broadcasts and WPT programs, play online.
4) Be honest with yourself. If you are losing, maybe your game isn't as good has you think it is.
5) Focus on the long term. Before you shout collusion or a rigged deck, think about the number of hours you've played offline and online and think about whether or not you have a good enough sample to make any assertions.
6) If there is a lot of raising and few showdowns (meaning no one calls the final bet) keep your eyes open since there may be collusion.
7) If anything seems fishy, PLEASE REPORT IT TO THE SITE along with the hand histories. The sites need to develop a history on the folks that are invovled in illegal activity.
8) After 7, mention the collusion suspicion in the chat box. See what happens. Somtimes the guys you accuse get pissed other times players will agree with you.
9) After 8, find a new table.
I compare places like Paradise, Party, and Pokerstars to big cities. Criminal activity (collusion, chip dumping, soft playing, probably software hacking (not so sure about this one)) happens but for the average citizen (player) he is safe from crime.
BTW, you mention "...F.ck the poor sap who gets buried every night..." Is he getting buried "every night" because he is a horrible poker player or because he is being colluded against? If he loses every night, I would argue that he sucks at poker and hopefully he plays for entertainment purposes only.