We've got a pretty good method to deal with our sales calls. It was usually easy to tell when someone would call and ask for the owner by name, but sometimes they can be convincing and end up talking their way past us to the owner. So we created a fake person named Tyler and started giving his name to sales guys. The fake owner name started spreading out around the sales leads network, so now when you Google Tyler's full name, it comes up as the owner of our company! So now when we get calls asking for Tyler we know right away it's a sales call. We've got a credit card in the mail for him once, and the other day we had some random guy walk in looking for Tyler!
For the digitizing guys, we started saying we sold our equipment and no longer do embroidery. Then they'd ask if we need any vectorization services, so we'd say we are closing. That didn't work, since I think they thought we were just closing for the day and kept calling. Some on a daily basis. So now we say we don't do any kind of decoration, we sell screen printing equipment. Inks and presses and stuff. That seems to work alright, but I think at some point those guys are just going down lists and don't really care or understand what you say.