Our old house (now where DD and her roommates live) was a real horror show sometimes. It was older (1950s) and hadn't really been renovated much since then - no outlets with ground wires, plumbing and wiring in horrible shape, furnace a nightmare, etc. Thankfully, though, most things worked msot of the time, until DP got sick. Thank God I'm handy.
The kitchen sink needed replumbing - the drains were leaking into the wall. We had a family friend, who was a contractor, offer to do it for us, at least the basics, and we would pre-pay for some additional work that needed to be done (she never did the work - her work partner absconded with the money and left her high and dry - so this was the ONLY thing that had a contractor at the root of it). She decided to do it cheaply, and bought flexible, corrugated pipes that have friction fittings for most of the drain work. This may have been fine, except that she didn't count on the friction fittings not working correctly, and that those aren't meant to be used with a garbage disposal. I had to replumb the thing, from scratch, at least a half dozen times, keeping the same parts until I learned better and bought the correct, glued fittings for most of the length (did have to have one flexible section thanks to poor design of the system). MANY evenings of sitting on a upturned bucket, under the sink. I got it fixed for good right before me moved.
The furnace. Ye gods. NOT vented, and so when we replaced it, they had to cut through the roof. Also, hot water heater in same closet had to be replumbed when it was replaced, as the overflow drain was going nowhere (plugged up and capped) and was a major hazard. Let the pros handle that - I wasn't about to tackle that mess.
Funniest one, though, was our waterbed. We had a king sized, hard side, waveless mattress that DP had owned about 20 years. Mattress sprung a leak - we spent two months on the futon in the living room, drying things out, including the wood frame (liner was as old as the mattress!) during one of the most humid and cold falls that our area had seen. We replaced the mattress and liner, and had it for three years of lovely sleep, until we got ready to move. We decided to get rid of the hard side bed and get a soft side, and just kept the headboard to re-use, since it matched the huge dresser we were keeping. For some reason, the siphon pump, the small electric pump, and the venturi siphon (the one you run water into from the sink) wouldn't drain this bed. I learned later it was because of the kind of wave less it was - you HAVE to use a strong pump. So I got a SUPER STRONG pump from Harbor Freight. Which leaked a cup for every gallon it sucked out of the bed, at least. And was half the strength it should be because of the leak, so it took three hours to empty. The entire time, I had to bail water out of the basin I had the pump sitting on, so it wouldn't overflow, and hold towels around other leaky spots. My back hurt so bad by then end I was crying. The floor was drenched, even with all this. Luckily, the kids pulled the carpets out in there - it was a HUGE mess.
I've learned my lesson - we had the new bed delivered, and made sure that the bed can be filled and drained with only a garden hose and the little venturi siphon. *sigh*