I do too, to some extent. I had an experience this weekend that fits. My partner stopped at a garage sale on her way home from work and found some things that she wanted, but didn't have enough cash with her. We went there later on to get two things. The family was in the process of moving, they had a moving van parked in the driveway, like they were ready to pile everything in that didn't sell and take it to the new house. My partner made an offer on the two items, lower than their asking price, but it was all the cash we had. I guess the guy got offended, said he wouldn't accept the offer in a rather rude way, and repeated in an even ruder way when my partner politely responded. It got me riled up, the guy was a jerk, and it made me want to cuss him out for being rude to my partner, but I kept my mouth shut. There were some other people there looking at stuff, along with the guy's teenage son and daughter, they were obviously embarrassed. One of the people offered to pay the extra $.50(!!) and we were on our way.
Afterwards, my partner was pretty upset, and she said that the best thing to do in those situations is to let the other person be a jerk, don't dilute their actions by being a jerk back, or mirroring their behavior. Hard to do in real time, but something that I've been trying to put into practice.