Someone should let the new members know that its kinda rude to advertise their auctions on other people's auction pages. :o(
That being said, if it bothers you, you have the option to hide their comment OR you can return the favor and advertise your auction on THEIR auction page! Your choice! :o)
But personally, unless the seller specifies that if you bid you can advertise your auction in the comments, you should never do what sourpatchkidd did. Its thoughtless and just bad form.