If you're asking me, Thrash, I found out from a writer friend of mine that certain websites enable the owners/admins to search for you on social media and other places as well by using your email alone. A lot of websites make you fill in your email in order to post comments, and that info is logged and saved. Apparently that's what happened and the owner of the publisher found me on Twitter and started following me. I talked it over with some other writers who thought I was being paranoid, and In the end I decided not to submit. I made a good decision because I asked around on Absolute Write and learned some not so good stuff about the publisher.
I am active on twitter, and the only time I hashtag is when I'm talking about editing or writing, never genre specific stuff.