Do you  mean Google Groups or the gmail?
I think you can filter based on gmail accounts and not miss anything.

I used Google Groups until today...
Jim

http://groups.google.com/group/rec.photo.equipment.35mm/browse_frm/thread/f2da1b
52378ad5f2#

I filter gmail, googlemail, yahoo.com.cn, and a few chinese domains and it
takes care of 90% of the sh.t that flows here.

If I filter a few legit posts to get rid of 90% of the spam, so be it.

This link:

<http://www.improve-usenet.org/>

suggests that filtering everything which comes from Google Groups is
the most effective way of blocking Usenet spam.

They're probably right, but what's prevented me from taking the plunge
is that I subscribe to a number of technical groups, where some expert
contributors have the habit of posting from their place of work,
unfortunately with the Google interface.

That means that I'd have to create a substantial "white list", and
maintain it.  For the moment, that involves more effort than putting
up with the annoyance from the Chinese shoe and tiffany jewellery
spammers.

Filtering on any mail address containing the string "@yahoo.com.cn",
on the other hand, unless you have correspondents in China, probably
won't produce any false positives.

I've used gmail since near the beginning of gmail (when it was available
 on invitation) as a legitimate web based mail.  In fact the fellow who
"invited" me was a rpe35mm poster.

Like Yahoo or Hotmail, it is indispensable as a backup e-mail channel
for travelers and/or just to have an independent channel from work.

I know a lot of people who use gmail in lieu of Hotmail/yahoo for the
simple reason that the user interface is clean and fast.  gmail provides
a lot more storage than I will ever need from it.

It is also intrinsically linked to the web based s/w that Google are
building (maps, word processing, spreadsheets, etc.) so there is the
build up of that side as well.  Not sure where that will go over time.

Gmail itself has fairly effective spam filters, so it does not get
clogged with junk as Hotmail or Yahoo (maybe they've improved?).

I actually have 3 gmail accounts.  2 personal and 1 for work.

Cheers,
Alan

Yes, on both counts.  But I don't post often so you wouldn't miss much.