I would normally grant an undo request without expecting an explanation if no new information was gained at the last step. On the other hand, if information was gained, I would normally ask for an explanation. I suspect this is a fairly common opinion on the matter. Some people do refuse undo requests altogether, of course, and that's their prerogative.
I agree. While it's obviously good sportsmanship to grant an undo, isn't it also BAD sportsmanship to ask for multiple undos in a single game? I have had multiple people give me a mouth full for denying their requests because when I asked for their intention, it was pretty obvious they rushed in making a decision.
I only ask for click errors, like if I click on end buy instead of done trashing or something when I have obvious money to spend. The amount of requests I get in return because they rushed is like 10-1.
If you misplay your hand and, say, make a choice that only lets you trash one card when you can trash two, that's on you!!!
Sports are about winning and losing. What is "good" about someone who knows how to play the game undoing his way through a game? Shouldn't that person just deal with it and know better next time? That's actual sportsmanship.....