You stick on a medium telephoto, have to go vertical, and the bloody camera tilts about the screw and the view sinks down to your socks. Worse: it didn't happen with my old 4/200 Nikkor but it does it now with even the 2.8/105! On two different tripods: a small, cheap-but-rigid Slik and a hugely expensive and heavy Gitzo and Gitzo head!
I hate things that don't work, especially when they are expensive and don't work.
Let me add my Fiat X1/9 to the collection: as close to the looks of a Ferrari as I shall ever get, underpowered in reality, traded at under two years because the factory loaded wheel-balancer weights directly to the alloy rims, and the general, on-the-house replacement of cathodic-damaged wheels ended before my dealer let me know...
Even with memory working in fits and starts, one could still create a long, long list of moments of intense anger. In general, we get a bum deal for our buck. Having just written that, I now worry about the new computer I ordered yesterday just before lunch.
Rob C