There's one thing that I'm wondering about. I usually buy foreign stamps and use them with my SASEs. When I get the SASE back with the autograph, sometimes the stamps aren't marked (they have no postal sign on them). Then I usually cut them out, put them on another SASE and use them again.
A couple of requests that I sent away like that didn't come back. I'm absolutely sure that I checked the stamps for having no visible printing ink on them. Did they undergo a laser scanning with optical sensors, or what?

Is there anyone who sent a SASE with "used" stamps and got it back?
Thanks for your assistance.
Greetings from
StOnEhEaD