Sleepless nights and misdirected anger with each other. I will say I never would have had the guts to throw someone out the first year, our toss happened last summer so I think you definitely tolerate less nonsense the more you see.
It's never easy nor stress-free to ask a guest to leave. However, the long term stress and possible property damages that might ensue from not asking them to leave far out weigh what you will experience if you don't.
I've asked people to leave and didn't charge them, just to be rid of them. You gotta ask yourself what you're willing to put up with and what is your limit.
I agree with the writer who said they would not hesitate to call the law if it required it. These days, idiots travel with concealed weapons. You don't want to get into a physical confrontation.