Once you've set up an alert within Mention, go to your settings and then 'Manage Notifications'. From here you can select the option to get a daily digest email of any mentions (I'd recommend doing this). You also have the option of getting desktop alerts - I personally find them annoying, but if you really want to stay on the ball then they could be a good idea.
Now, it is not that these sites are not interested in Google users. In fact, they have hired us to help them increase their share. However, they are getting so much traffic from sites like Facebook that it seems there is less urgency about attracting this traffic and less willingness to change the site to meet organic standards. Not long ago, sites would urgently and unquestioningly abide by Google’s standards to court that traffic.