I used to be in a group of 10-20 guys who would meet in Las Vegas every year. We developed rules, one of the most significant being that one person just picks up each bill, whether it be restaurant, taxi or whatever. None of this "well, I just had the cottage cheese and iced tea" stuff for us. We were all friends, and we knew it all averaged out.
One year, a guy we knew to be a cheapskate invited himself along. You knew it wasn't going to work when he decided to stay in some off-Strip, William H. Macy in The Cooler-type motel as opposed to the reasonably low-priced Strip hotel the rest of us were in. (Note that the guy was a well-paid engineer. He was just cheap.) Then the new guy got all worked up when he was told about the payment rules and informed that it was his turn to pay. He eventually coughed up some money but never took his wallet out for the rest of the trip and basically tried to do the rest on the cheap. Not exactly the attitude we wanted to have on our annual gambling outing.
The following year, when it started coming up on trip planning time, he started asking about dates. I said we weren't sure we were going, etc, and I'd let him know. Of course, we planned the trip privately and had a great time without the cheapskate.
Mine is not really a horror story, but a dear friend and I just got back from a RTW. We have very different spending habits, and it seemed that I ended up paying half of her spendthrift bills. She's the only person that I've ever eaten with that orders 2 meals or 2 desserts (it was in France, but still...) just to try them both. She ordered a $40 bottle of wine, I had a glass full at her insistence, then ended up splitting the bill when checking out of the safari camp. I was happy in the lounge with free snacks, appetizers and wine, she wanted to go to the restaurant. Her spending habits are far different than mine. This is a dear friend, that I want to stay dear friends with, but splitting the bill during the trip, by the day, or whatever seems to still be costing me a bundle.