I guess I have been very lucky. I have been in numerous partnerships and I have only had two that did not work out well. The first involved a set of cows we purchased in a sale in Kansas City that had been brought over by the Irish government, and sold in a sale at Curt Rodgers place . We purchased 8 bred females and we ended up not getting them into Canada, as we could not get them to pass two successive blue tongue tests. ( Ireland is bluetongue free, and these cattle were only in the US a few weeks prior to the sale, so I suspect the test was very inaccurate). After having them sitting near the Canadian border in North Dakota for 16 months and testing them monthly, we ended up leasing them ( and now two sets of calves) to a breeder in Illinois. It was a disaster and after not getting cooperation for almost three years, we had them picked up. I phoned a man I know who lived fairly close, told him the story and he agreed to do pick the cows up. He had more intestinal fortitude than I would have had, a she simply drove to the farm, told the guy to get the cows in, and loaded them.
The second one that did not work is more recent. I partnered with a breeder that I has sold several cattle to, in Maryland, on a female in a sale in Nebraska. Prior to the sale, we agreed on how much we were going to spend. I was going to be away so he agreed to do the bidding via the phone. He bought the female for twice as much as we had agreed to. I refused to pay for my share for several months, because of what he had done ( my share was $6200... and he still owed me another $3000( from another deal we had) that he agreed he would pay on the female that was purchased. The sellers of the female started to phone me regularly... and I ended up being the bad guy in this. I finally paid for the female as I thought mu reputation was worth more than 1/2 a cow. To this day, I have not received one cent from my partner in Maryland. He did phone me a few years ago and he said he was selling two daughters, a son and some embryos in the Ohio Beef Expo and he would pay me after it was over. Still haven't seen that money either. A rather important lesson learned... your partner is as important as what you are buying.
Other than that, I have owned many herd bulls in partnerships,and I now own several cows in partnerships in several places. All have worked out well. Maybe I have been fortunate, but I certainly make sure i am comfortable with my partner before I get into the partnership.