Most gigs in Manchester, the headline band brings the drums and the bass amp, so a lot of the time, you are obliged to use the headliner's rig. It's turned out that we've headlined in these situations that i've had to let people use my amp, but not many people round here have Ashdowns, it's mainly Hartke or Behringer from what i've seen and the odd Fender, so i take it upon myself to make sure they are using it right. I went to have a look at the settings on the amp after one band had been on, and all the buttons were switched in, you name it - bass boost, treble boost, sub bass, the lot.
I don't have to worry about someone asking to use my bass as it's the wrong way round for 9/10 of you. If i knew them then i'd maybe consider it, but as someone alluded to previously, if you batter the crap out of your bass and then expect someone to lend you theirs when a string goes, then frankly you're having a giraffe IMO