For live recordings, I think it is a complex issue. I don't mind minor fixes and sometimes wish it were done for glaring errors. For example, on Secret World Live, Gabriel comes in too early for a section of an otherwise wonderful In Your Eyes. I wouldn't have minded if this was fixed so that the proper lyrics were sung at the proper time. It wouldn't have needed much re-recording. The part he sang could have been shifted to match the section and one line would have to be imported from another recording (or added from in studio). I know many mistakes can "make" a live performance, but this one doesn't for me.
Another fix I can live with is on The Who's Live at Hull. The bass wasn't recorded for the first few songs. However the performances were close enough to Live at Leeds (the previous night) that they could patch in the bass from that performance and do a bit of fixing to make it work. I prefer that than listening to the first few songs with no bass track.
Obviously I'm not big on a live album where much of it isn't live at all. That's fixing too much and you are no longer getting a live performance.
And there are fixes that are just plain unnecessary. The crowd noise mentioned above is one example. Live at Leeds has very little crowd noise and yet it is probably my favourite live album.