I joined a Lootmaster "ponies given in order of joining the party" farm exactly one time, and while I DID get my pony (I was second in line, after the party leader), only three ponies dropped after three hours of farming, after which the party broke up. This made me feel pretty guilty, and I now consider Lootmaster parties to be a very shady form of farming for these kinds of rare drops. I will not participate in them, even if I have a strong chance of getting the drop - because half or more of the party has essentially been tricked into helping the other half or less get their drops for very little chance of reward.

I do not consider it to be "cheating", persay, if it's clearly spelled out in the Party Finder, and it's certainly possible that the party leader FULLY INTENDS to stay long enough for everyone to get a drop (because they don't really understand just how bad the drop rates really are). Nonetheless, honest or not, those party leaders are fooling themselves, as are the folks who join the party after the fourth or so member.