In one match I served what I was sure was a fault, the guy plays it, I stand there and watch it.
"I played that as in" he said.
"Oh," I said, standing there.
"Have a second serve." he says.
"Thankyou!" say I.
Then, later in the match, the opposite happened; I played one of his serves that he thought was out, he stood there, and I offered him a second serve, which he accepted with thanks.
We both knew the rules, and I guess we both broke them, but it seemed like a reasonable thing to do.
I now try to be more careful to play all points where there is no out call on the serve.
It annoys me a bit when people say nothing on on a close out serve, so I'll generally go to switch sides claiming the point. Then if they say, "no, that was out," I'll politely say that I need a call.
One match I was hooked mercilessly by an old guy who would stand there waiting for a second serve after I served one that I thought was good. I was inexperienced and let him get away with it - thinking I served lots of faults that day - only to be told by my team mates that a lot of those "out" serves were really in.