The seller will see the Positive, Neutral, or Negative rating you give him. He will also see any critical comments you make associated with the rating, as can any other ebay user who cares to look at his feedback. The member-id associated with the feedback you gave will be "scrambled" with only two characters from your member-id in the clear, so in that respect, the feedback you left is anonymous. He may make an "educated guess" of the sort you mention.

However, the detailed seller rating (DSR) give by a buyer is anonymous. ebay states there will be reports available to the seller summarizing how his DSR's are stacking up over time but not identifying the DSR from any particular buyer.

A seller can choose to make all his feedback "Private", which means none of the ratings and comments he receives will be visible. Many would choose not to deal with a seller who made his feedback Private though.

http://pages.ebay.com/services/forum/feedback.html