It depends a lot.
I remember one incident. I was playing a casual game with a friend who generally expects to go home with the best painted award. His army that night was a work in progress, most of them just primed or still grey, but he wanted to see how they fought. Another regular walked by, saw all the grey, and sneered. I took great pleasure in picking up one of the few prototype models that had been completed, and presenting it to the sneerer.
Hehehehehe.
Since that time I have made a point not to grumble about armies in 'Imperial Colors' (silver and grey) so long as a few more models are painted each week. Any player who is trying to do it right shouldn't feel peer pressure to do it quickly.
On the other hand, I like the mega battle rule that everything has to be painted. That is just a show. What's the point in putting down a zillion points of models unless they're all painted?
So it all depends. In general, I don't like the snob attitude of sneering at any player for any reason. If we're going to grow the hobby, let's not try to drive people out of the store.