There are two ways to exclude sellers. One is used during a keyword search,
and the syntax is &se=userid1[+userid2..] e.g. &se=8081126001.
The other is used in category searches, like when you're looking at all
metalworking items within the Seattle area and you don't want to see the
idiot who sells manuals. That syntax is e.g.:
&sasellerex=25119449+1796081+111379987+70671053

You should know and become familiar with both of these. This would have
worked to 100% exclude Al Babin back in the day (if any are still around
who remember that rascal). There is no direct way to find a seller's internal
ebay number. If they have an "ebay store" then to get the sellers id place your
cursor over their store in the listing and see what the url is in the status
bar. It will have id/1580591 or some such. Your exclusion qualifier will then be
"&se=1580591" (omit the quotes) tacked to the end of your search url. If they
don't have an ebay store then get their seller id (e.g. "reliabletools") into
your cut/paste buffer and go to Search-By Seller and then put some dummy
keyword in and the seller's id down below and then click "Search" and examine
the url of the following page - it can be inferred from that.

This sounds a little tricky, and in fact, it is. But it is hugely useful and
I use this all the time. Guys on this NG are so smart you shouldn't have any
real trouble with it.

Grant Erwin
Kirkland, Washington