I tend to add people back who add me, as long as you don't appear to be a bot. I use locked posts largely to foil search engines and protect the privacy of others.
A note to Russian speaking livejournal folks. I seem to be getting some new friends lately from the Russian side of the web. I tend to only add journals back if I have some idea of the person behind the journal and I'm embarrassed to admit that I can't read Russian. If you'd like to read my flocked entries (not very many) please leave me a comment in English and tell me a bit about yourself on one of the entries. Thank you!