I think it's not cruel if you're going to dress up your dog just for a short period of time, let's say for a couple of minutes, for a photo shoot. But to let him stay in those clothes the whole day -- that is cruel. They would get all uncomfortable and it would actually show. They would flinch as if to let you know what they are actually feeling. Unless it's winter, try not to dress them up for a long time.
I don't think it's cruel if it's to keep them warm in winter. I have a pitbull (very short haired) and live in New England and I think it'd be cruel to drag him out in the freezing cold without something to prevent him from getting too cold.
I also think with "intimidating" breeds sometimes doggy clothes (when they won't overheat the dog) can help make it so people freak out a little less (people are terrified of my dog when I'm out walking him even though he's the gentlest, friendliest, most polite guy, so I bought him a sparkly pink collar and it seems to help)
