As a seller that sells quite a few things I find it sensible to do feedback weekly. I used to leave feedback after the customer had paid, as you're right, they've done their bit, all I have to do is my bit. But, there are so many uncommunicative morons out there that don't read the description properly and don't even query with you before they simply leave negative feedback. Most recently this has happened with people that have bought an e-Book and were waiting for a printed book. On my most recent neg (user id: chrisperkins) the buyer emailed asking where the book was. I told them I had emailed the link weeks ago, and repeated the link. I also said that if they were expecting the printed version, that they could upgrade and get that too (for about £2.50!). They didn't reply...I simply got a neg saying I was a con! If you look at my ebook listings, I have been very careful to mention on a number of occasions that the product is a digital ebook. I have hundreds of satisfied customers that can read, but still I get twits like the last chap leaving negative purely because they're illigitimate illiterates! So, I save my feedback, just in case that happens, in which case I can leave the a throughly deserved neg in return for being a complete plonker.