When I did more side work I had a special rate for people who were a pain in the rear. I had one client who had me look at his system some outlook issue. I told him straight up it would be like 3 days before I could even touch it. No problem he needed it fixed.
I get to it the day I said I would, spent about 30 minutes with it (had it at my home at the time in my work area in the basement). I used to keep an area where I could have stuff just sitting chewing away so I could work on multiple things if I needed to.
I get a call from my wife, the guy called her and started yelling at her how he needed his computer and ran 3 businesses from it. Belligerent enough that my wife was almost shaking and hung up on him. I tried to call him. He's very fortunate I got voicemail. I'm a Christian and not someone to swear, that gentleman (using the term loosely imo), nearly saw a side of me that felt like punching his lights out. I was originally going to charge him something like 135, my rate was 40 dollars to diagnose and about 75 per hour. So to fix outlook and give the computer a virus checkup, that is fair I think. Stopped working on it right there, returned his machine at my pain in the rear rate of about 250 bucks. Which I'd given him a price range at the beginning, that was the very top of it. I don't do as much side work now, not as much time as I drive an hour one way to my normal job (IT helpdesk, network guy etc). But i got to where if I got a vibe that someone would be a pain to help, I just priced them out of the ballpark to where they never called me again, or just didn't answer the phone.
I had one client I helped out where they'd built a gaming system and somehow the cpu burnt. You probably remember the FX 6300 CPUs and the 6100s how bad some of the stock cpu coolers were. I had time into diagnostics etc, and quoted them a little higher than market price because I have microcenter about 45 minutes away, and was going to get them there CPU from there, plus get their replacement plan in case of issues. I get a call from them about why was it a higher price than Newegg or something. Kind of thinking, hello, you are getting it locally, don't have to wait for shipping and get a 2 year replacement in case of problems (with microcenter you can take it directly to them and not even deal with the manufacturer if you have that plan). Then once a client called me on Christmas morning to ask about crossfire. Kind of like, hello, it's Christmas morning with my family and you are calling me just for advice?? I Don't mind helping people, but be somewhat respectful in return.