makeshiftapparel: you most probably are right as for bots (there are bots everywhere, kind of an invisible invasion ;-) maybe after all my stuff is mostly seen by blind pieces of software LOL
MysticHillsNgaroma: I tweet about items I post on my shop. Since I can only create items at a slow pace, it does not look like spam. Additionally I post about what I am currently working on, even refer to pictures of items under construction that I put on Flickr, I tweet about the supplies I buy and sometimes where I get them in order to help promote other businesses, I tweet about things I like a lot. As long as I'm not flooding, my followers seem very happy
Also you can achieve conversations on Tweeter. It usually starts on my side by a reply to an existing very recent tweet, and I make sure the targeted tweeter user name is in my reply. Then I receive a reply and the conversation goes for some time... all public by the way. You can also send private messages if you want