I don't ask permission to pass, but I always warn or give notice. I ususally try to do it only one gear faster than the horse I am passing. "PASSING AT A GAIT ON YOUR LEFT" or "PASSING ON THE RIGHT"
I tend to return politeness with politeness, but rude people get on my nerves, and although I try to maintain the moral high ground, my patience wears thin.
If you are on a snails pace, move over and let other people pass when you come to a wide spot, or prepare to get upset if I fly past you on the inside of a curve. If someone comes up behind you it should be pretty obvious they are moving a bit faster, go single file and let em by when the trail permits.
If your horse kicks, don't block the trial and tell everybody it kicks, "GET OUT OF THE WAY"
If you decide you need to adjust tack,Again, GET OUT OF THE WAY!
That last one drove me nuts, big group ride, narrow steep uphill section of trail, a rider decided right at the very top was a good spot to get off and adjust tack, 15 or so horse traffic jam casued by said rider, and the couple people behind them that just sat there and didnt say anything.
Don't stop half way up a hill, or stop when you get to the top, jamming everyone below you.
Do stop at water, and let the other horses drink.