Yeah what to do with old stuff is always challenge. When it’s your stuff I find it harder as to when to replace, with someone else’s it’s better to be safe than sorry. Thanks for sending me pictures of those frames. What I see is that something has been eating the wax off and I presume it’s mice which is no big deal and I also see that some of the foundation is missing or eaten away which may tell me that the foundations are probably fairly old. If you know and the foundation is six or years or older I would pop the foundation out and toss them.
If you don’t know how old they are, you could save a few bucks by doing that and some beekeepers would suggest scorching the frames as well. That will ensure any bacteria or spores are toast. With what I see, I’d take anything that is black and toss both the frame and foundation if money isn't an issue. The outside frames are probably less used by the bees and maybe able to salvage those, again we still don’t know what’s in them.
When you buy used equipment, you never know what you are getting, even if you ask. Maybe the original owner didn’t know or does know and is not telling you, which is worse yet.
In regard to, scraping the wax and melting it down, I think you’ll have pretty dark and unappealing wax.
