I was recently added to two google groups without being asked or permitted ! That, IMO, is bad etiquettes. I used the "Google Groups Abuse Reporting" ability provided with the first email that came from the group, to indicate that the owner added my email-id without permission (this was a simple radio button click) and also provided the Message-ids of the emails that came in.
And, Google sent me this automated reply. It certainly doesn't invoke extreme confidence that anything positive will be done to owners of such groups who add members automatically.
Thank you for your note. Google does not regularly monitor or censor postings sent to Google Groups, but we do try to prevent wide-scale spam and other forms of Usenet abuse. Please be assured that the information you sent to us is being collected and taken into account. While we understand how annoying off-topic posts can be, we aren't able to pursue most complaints we receive about them. We are using the information you provide to make large-scale improvements in preventing abuse. We appreciate your help in our efforts to increase the quality of Google Groups.
Replies to this email address will not be received. If you have a general Google Groups question or wish to report a post that you suspect is illegal, please write to us at email@example.com
The Google Team
FWIW, Google Groups does provide an ability to cut off further unsolicited subscriptions. However, for me to be able to exercise that, I have to sign up as a member of Google Groups (forcing me to!) !!