The eventing community is pretty close. I groomed for a season before I even got involved with competeing, so I saw a lot of stuff you would normally miss. I saw a trainer hand out her own coolers to people for their horses who didn't have them on a very very cold, wet, nasty day. I have seen some very confused people on course walks get helped out by other trainers. One of the girls I groomed for didn't have a correct color coat and another competitor lent her a very nice, very expensive jacket for dressage and stadium.

I have not seen trainers warming up other peoples students. Just because everybody rides so differently and every eventer is so different you kinda have to know the horse and the student. When my friends trainer was too busy socializing with other people to come warm her up, I warmed her up before cross country.

There are some trainers in the area that I know and I will take advice from and there are other that I will ignore. I know who to ignore (like the trainer who insists that shoulder in and half pass are the same thing), but if somebody I don't know if offering advice when I am having a problem I will at least try it.