I only join bounty with good design. not care about anything else. 
)) sometime I take nothing but it's ok. Normal What kind of design you are talking about ? Signature design or projects webpage? Set of signatures can be bought here just for $10-20 and design - depends on the budget. Some free design templates looks better than those who are made by professionals.
Share your experience with us. Is your tactics working in most of the cases or not. Frankly, I would not recommend joining bounty just because it has nice design. The design is one thing, but content, product and team are what makes project successful.