My thought process on voting/faving for what it's worth. To me it's a degrees thing. Knowing that votes count a bit towards the search process, if I vote for something, I like it and think it's salable and deserves to be higher in the search. Because "favorites" are visible to whoever might actually click to look at them on my profile, my thought process is two-fold on those. One, if I won the lottery and had unlimited wall-space, I would buy it. Two, I don't mind essentially endorsing it. I may be over-thinking it, but that's my methodology.
I don't get into the whole vote for me, vote for you thing. If I have time when someone comments, etc., I'll go check out their stuff. But I hope they didn't do it expecting reciprocation and I hope people don't think I expect it if I comment, etc.