Mappers who blacklisted them self should not be allowed to rate or comment on maps, its a very coward behaviour to hide from judgment but at the same time judge others.

I've had this come in a few times. I don't want to completely disallow rating or comments, but there are some things that can be done:

1. Manually lower the weighting that blacklisted users have on charts & averages, even maybe completely
2. Forcibly hide their ratings on the front page and map pages
3. Forcibly hide their comments on the front page

Completely disallowing seems a little extreme to me - some may still want to use the site for cataloguing purposes.

I agree with moonpoints suggestions for ratings, but I don't think these people's commenting should be restricted since blacklisting maps doesn't affect commenting