I like to post and receive Kudos because I'm not a well established seller on these boards. I sell every now and then but I hope to sell more soon. I'm just so busy with work and life it's hard to post a selling thread frequently.
I want to provide the best buyer experience I can give..i.e purchase price, grading, fast shipping, books well packaged, communication...etc..
So I think for me right now Kudos helps some. I don't know how much but I think it does help for lesser known folks who don't sell that much.
I always try to post Kudos if someone wants it and I usually request Kudos especially If I sell something.
It's not that much effort to post Kudos if someone provides you a link.