It pisses me off to no end when I get a link request from a site that looks ok but after some looking see they are blocking them through one means or another to get one way links.
i use to just delete the request but now I have taken a new approach when discovered and it works.
Below is an example of my email I sent this morning. Hey I know it isn't polite but I really don't care because it they get message loud and clear.
This is an example from today.
Clay what does your company think we are fools here. I am going to tell ya this you keep blocking the pages in robots.txt
Get rid of this or I promise to go over all your linking partners and send them an email telling them your blocking their links in your robots.txt file. Then lets see what your ranking do in Google when all your links go away.
This is your only warning delete it or suffer the fate of being a dirty underhanded cheap site. I have no problem going over all your links and sending this email to all of them at one time. Been doing this for 10 years and it pisses me off to no end the way cheap sites such as yours try to game the system.
I have cc'd a couple of your linking partners in this email just to show you I will follow through with what I say. You had better be glad I am letting you know because I could just do it and kill all your rankings so delete the robots file.
I do this if they are doing a redirect 302 and so on. I will follow up on my threat as well but as the one from today I go back and guess what the robots.txt file has been changed.