Do you clean your seed or send the whole head? They are a pain and I have enough to cover the world. Twice! I didn't care much for them because the stems weren't very strong and they fell over from the beginning.
I usually clean my seed, but as long as the recipients know what they're getting, you should be good. Once I was bummed after a trade. I don't think they realized, all I got was chaff, but all of the seeds had already been dropped. Too bad on their performance. Mine are upright, but it's been such an odd summer, I didn't get any flowers.
I agree with Lisa. Just let them know that the seeds will include chaff. I don't clean all my seeds. I let them dry in paper bags, shake, remove as much of the big stuff as I can and then package the rest. Even if I question the viability of the seeds, I'll include that in the communications during the arranging of the trade. Last year I had seed heads of Achillea Cerise Queen which Stage Rat wanted so I let her know that I didn't know if there were even seeds in there since I didn't know what they looked like and it didn't look like the pods had matured. None came up, but it was more or less expected. This year the plants are producing mature seeds which I can see so I'll send her some more and we'll see if these are viable. As long as the recipient knows where they stand...
I grow Coreopsis Domino which I truly like. A nice bushy plant with loads of yellow blooms with a red center. I tried something different though and chopped them down a bit in early June. The four plants I did this to stayed nice and compact and didn't flop. Still bloomed like the dickens!! I'll be doing this from now on with them. :O)