Writing Business Checks With Clauses?

[Gabriel A.]

Every now and then, I'll receive a legitimate check in the mail with a warning that by endorsing it, I'll be agreeing to sign up for an insurance policy, a magazine subscription, or whatever else.

Anyone know about the legality of these checks or how I can begin writing them against my own business accounts?

I'm interested in offer $X for a lien, and mailing my check with the offer, with the stipulation that by cashing it, they are agreeing to assign lien to me.

Thoughts?

Gabriel