Ours is a self build green merc, with only one side window. We have just spent almost 10 weeks travelling round Spain & Portugal. We've noticed a lot of the "white" campers tend to be wary of us, and not particularly friendly until we have stayed somewhere a couple of nights - probably think we are gypsies. The only problem we had was when we parked in middle of a Spanish town, which probably wasn't the best of places, & we had to make a quick exit when some of the local youths decided to see if the van was emptly by shouting a lot, & giving the van a bang on the side. With hindsite, they were probably seeing if it was alarmed, as I don't think they knew we were in it, but it only took us 5 mins to move on.
I often think I would like a nice shiny white camper, but realise that ours lets us go to a lot of places that "white" ones can't, as we are often assumed to be a delivery vehicle.