Never trust a squatter, or anybody in fact, who justifies the solidity of their experiences by quoting time. ie. "I'm an experienced squatter, I've been squatting for nearly four years". Means nothing.
It means nothing, because it gives away nothing about what you've done. It sounds like the kind of puffed-up chest to get the girls but disguise all else. You may have squatted for four years and been a slob the entire time, for example.
Unfortunately for us, we're having to ask our flatmate Rhoderocker to leave, for these very reasons. Leaving his vomit sat in a bucket in our hallway for three weeks last winter was the last straw to add to our haystack of last straws.
On behalf of the squat, I asked him to leave today (with seven days to get out). He couldn't see my reasons why, but he couldn't dispute them either. "In all my four years of squatting, I have never...." -- yeah yeah -- "...been thrown out of a squat". Followed by lots of expletives. All noise and bluster, but I know he will be gone by next week. I know because he knows I know.
So, a tip for the future -- interview your new squatmates with care and give them a trial period in exactly the same way you would if it was a rented house. It shouldn't make a difference because you squat. Squatting doesn't mean you'll get better flatmates, it's still going to be a flatshare/houseshare after all. You should not be coloured by the fact that your (potential) flatmates may share the same interests/ideals as you, ie. all activists/vegans/etc or on "the scene".
Paying rent may encourage "I've paid my rent, I have the right to do whatever" when it comes to how tenants conduct themselves. Interestingly enough, living for free may actually encourage the same. Don't let them get away with the excuse "But it's a squat". You'll live healthier for it.