It happens that innocent people are charged criminally every day. Note that I didn't say that the majority of criminal charges are unfounded. However, don't think that just because you didn't do something illegal, you won't get accused of doing something illegal. Having said that, I wouldn't want to cause a law abiding person to stay up at night imagining that they are going to be whisked away to jail in the middle of the night by the SWAT team. That's called paranoia, and it's not what I'm trying to engender... Here's what I am asking you to worry about: If you are hanging around people that are up to illegal conduct, you are at far greater risk of being criminally charged for something you didn't do. Consider the plight of 96 young men arrested at San Diego State for alleged drug sales. Are all of them guilty? The truth is, I don't know. However, based on my experience, I would guess it is likely that some of the arrests were made largely by association. Whether it was membership in one of the fraternities targeted and/or being a recipient of a group text message or an email by a drug dealer concerning drug sales, it is not unlikely that at least a few of those 96 never sold drugs, nor did anything in furtherance of drug sales. If a large scale sting operation can happen at San Diego State, it can certainly happen at UCSB (and probably already is happening). So, aside from quitting your fraternity, and disassociating with drug users (which may have its advantages), what else can you do to protect yourself from being falsely accused? Well, first read about what happened at San Diego State. Young looking cops working undercover befriended fraternity members by showing up at parties and acting like college kids.
Ask yourself if you really know the people you are hanging with. What is it about them that would cause you to conclude that they couldn't be a cop? What you shouldn't ever think is that they are not a cop because you saw them get drunk, get in a fight, rent an apartment in IV, get high, buy drugs, share drugs, or sell drugs. You should neither rely on any statements that they make that tend to suggest that they are not cops (including, but not limited to, "no, I am not a cop", "I hate cops", "cops are pigs", etc.) The thing to understand is that cops are not only capable of lying, but lying is part of their day to day professional life. They lie frequently when they work under cover, and even in uniform they lie when they are investigating crime. They do so with the complete approval of their department when it is done for an approved purpose. In fact, they are trained to lie. Unlike any other set of professionals, they may lie with absolute impunity. What other group in society can say that about? None. Even used car salespeople (and most certainly lawyers - sorry, lawyer haters) face negative consequences if they are caught lying.
Another thing a UCSB student might do to avoid getting roped in with those who are up to no good is avoid people who are not affiliated with UCSB. It is true that a lot of City College students live in IV, and are, perhaps, planning to transfer to UCSB next Fall. However, if you don't go to school with them (i.e., see them in class, etc.), do you really know that they go to City College? And can't anyone, including a cop or someone who is up to no good enroll in one class at City College at a minimal cost and hassle in order to "fit in" in IV? Of course they can.
The best thing you can do to avoid being arrested is to obey the law. And to greatly limit the possibility that you will be accused of something you didn't do, you should avoid those who are breaking the law.