I don't think fav-and-run is always a bad thing; far from it. I can perfectly understand fav-and-running if a work already has a lot of comments and there's nothing new to add, or if you've already commented on the artist's other works, or if sometimes you just can't think anything to say. I do generally appreciate favs with or without comments.

What I don't appreciate is checking my messages and seeing "x has favourited your entire gallery." No comments. If my work really means that much to you, if you love it all so much you'd consider it to be your favourite, then how hard can it be to leave a comment? One meaningful comment is worth a thousand favs.

If you fave one or a few of my submissions, it tells me you liked those more than my other stuff. If you fave everything I submit, it tells me nothing other than "this person clicks a button on everything that turns up on deviantWatch".

I know I'm not a very active member and my art is far from outstanding. I don't expect a lot of comments and favs, and I don't mind logging on and seeing no new messages. But when I get a message, I'd like it to mean something. If you're going to fav everything I submit without ever commenting, then please don't bother.

tl;dr: I don't mind a few fav-and-runs, just don't go overboard with it.