As stated, in a non-officiated match it is often pointless. But I will definitely shame the person mercilessly, and I mean mercilessly. I would make mention every time they did it because it is cheating, and I won't let them forget that. It reminds me of a college match I played many years ago, before on court refs were the norm in college matches. I was playing doubles at a big tournament at a large facility and our match was sent to the farthest court from the tournament desk. One of our opponents blatantly foot-faulted. My partner mentioned it right away saying we don't want to disrupt the match by having to walk back to the TD to get a ref and could the guy just back up a step. The guy continued to foot-fault the rest of the game. So, on the next game when it was my partner's turn to serve, he started walking to net before his first serve. I thought he was going to tell me something but instead he walked up to the net and slammed an overhead shot into the service court that then hit the fence and said loudly '15-love!' The opponents said, 'What was that?' My partner said, 'If you're going to foot-fault so am I'. On the next point my partner again started walking toward the net. The opponents then said, 'OK, OK, we get it'. There were no more foot-faults and we went on to have a good match. Foot-faulting is cheating, plain and simple. It doesn't matter 'if it's just a little' just like a ball 'just a little bit out' is still out. Foot-faulting a little is like being a little bit dead, it is what it is, cheating.