Same experience as Jazz really, we go out every weekend around South Yorks / North Derbys - Notts etc and very very rarely see non-soulies gawping or trying to 'do the dance'.
There are some who look as though they've never danced 'Northern' in their lives, but you can see them mouthing the words to songs that you wouldn't expect them to know, so....
On the few occasions I've seen the odd drunk, or non-soulie, they didn't really seem to be taking the Mick, they were watching and trying to have a go - in fact I was talking to one youngish lad at an all-dayer, who was a bit drunk and seemed to know nothing about N Soul but to be fair, he really liked what he was hearing and was fascinated by the dancing. So there could be a positive side to the younger non-soulies turning up and having a look....but for the late middle-aged 'motown morons' there's no hope.
Maybe it's not as bad as you think Barney, you go to J36 and the like don't you?... I reckon we're OK for a while yet. Should be easy to spot the crap do's.