I'd generally look for colourful and clear artstyles.
If I find a VN with an interesting premise, I will try it out regardless of the art unless it is absolutely intolerable (i.e. art is really really really old).
Yea, I get what you mean.
I actually almost dropped Little Busters because of those reasons. It was an amazing VN, but after coming from DC II with it's great artstyle and UI, I had to just forced myself until I got used to it.