I've taken my girls to auctions before. They are 10 & 11. Didn't have much of a choice as Grandma (primary babysitter) was outta town and Dad was working. They had a blast and
most everybody enjoyed them. Of course they are being raised to be polite and are always (yeah right) on their best behavior (in a setting as such) or they know they don't go again.
My youngest didn't enjoy it much and my eldest......just like her dad....."Mom, did you see blah....blah....blah....." 'shhhhhhhhhhh!!!!!'

I think it depends on the kid but more so the parents. The last auction we went to there was a guy there with about a 4 year old girl. She was, for the most part, well behaved. What irked me was her dad didn't bother to 'watch' her. Often she was getting underfoot of many people.
Heck we had a local auctioneer bring his toddler to one of his sales.....now there was a handful of kid!!
Grin and bear it........