I like my bugs solved, especially in games.
When there is such a bug I like, then it is the Windows bug where the mapped drives are connected but not accessible.
My favorite bug was in the tip of a flying macine in WoW called Oghrim's hammer or something like that. At first, when you flew into the small hole on the tip, you wouldn't be able to get out of it without using a hearthstone. Naturally, my friends and I had a blast trapping each other in it (we could log into each other's accounts or lead each other into it).
My second favorite bug was probably dead-angling from Dark Souls 1. If you swung at someone while facing away from them with a wide-swinging weapon, and still hit them, you could ignore their shield, even if it was being held up. I personally feel this bug did a lot to help larger weapons compete with speedier small weapons in PVP.
My third and fourth favorite bugs happened in Tes4 oblivion. Paintbrushes would float when you dropped them, so you could stand on them, and build stairs. Also, You could get wonky with a bow and arrow to replace the arrow with something else, like watermelons. You would then shoot the arrow and a number of watermelons would come out of it according to how many arrows you had.
While playing Vanguard SoH there was a new quest for a unique mount that took a bit of work to get. I did some grinding for a few days and got mine fairly quick. Happened to notice an NPC merchent would buy it off you at an exorbitant price (50gold? Was a lot at the time while the game was still new). So I sold it and within a day or two it was patched to be a fraction of what it was.
I ended up using all the money on crafters to build 2 boats, for me and a friend, and the rest building a house.