I have modified this guide to remove the example of how it was done, as that caused it's removal by ebay, so here is the non-interfering version of the guide.
Someone somewhere, has found a sneaky way to add items to anyones watch list, this guide is to warn you about this. Basically, items can be added into your watch list, without you specifcially adding them yourself.
I am not allowed to illustrate the point, as the original guide did, so you will just have to take my word for it..
Keep an eye out for it happening, and if items start adding themselves, report them to ebay.
It has been suggested, on at least one weblog that this could be used in the ebay forums, to add items automatically to everyones watch list who reads certain posts, not sure if thats true, but it does work in lots of other circumstance, any item could be added, even ones that most people would find offensive, so lets hope ebay picks up on this and sorts it out!
It can also be used to artificially get items into ebay pulse pages, so keep an eye out for items that mysteriously add themselves into your watch list. It probably does not mean you have been compromised, no one need have access to your pc, or your password, they could just be utilising the loophole (which does not require your password, nor "hack" your system in any way)
If ebay has not heard of this, then feel free to ask me, and I can provide details of how it was done, but lets face it, I found out about it on the internet, and its all over the place now, so just keep an eye on your watch list for items appearing from no where!
Its a fairly innocuous innocent loophole, but it does need fixing, as pretty soon every dodgy seller will end up using it, and my watch list would fill up pretty fast! Ps, its pointless emailing asking how its done, as I wont say!