I don't have a problem with resellers. I can make a deal with them far easier than "normal" trader - which are anything but "normal". The guys with 10 or 20 keys worth 1€ or 2€ each outright refusing the games they claim they want?! No, sorry. I'll never consider that normal.
Out of morbid curiosity I dug up your trade offers.
I only found 5 attempts to trade for final station.
Wallberg owns everything you offered already. As for why they're on his wishlist, i presume for card farming (he runs a card set bot, selling for keys). The value of cards obtained even at 2:1 is of too little value in his mind for TFS. Grey market has no meaning in this case.
CHOKOMA and SaiNT have nearly 90% decline rates. I can't see a pattern to why they accept what they do. As a completely wild guess, dungeons has an abysmal H:W ratio nearly 10x worse than TFS. For heileen, its base price is 1/3 that of station, and it could be that the individual views humble keys as far more valuable than indiegala sourced freebies.
I can't get a read on Lon, but again, 90% decline rate. My guess is similar to before; Humble purchased key cost more than a fanatical sourced one. Grey market irrelevant, it's about what they paid for it at the time.
Ishmael probably declined for the terrible H:W ratio, almost 10x worse again. 95% decline rate to boot.
So in summary:
1. You picked people with astronomical decline rates and expected them to accept
2. You assume they care about grey value, which they didn't
3. You offered extremely common and cheap items in exchange, when you may have been able to make more appealing offers
4. You didn't make any attempt to clarify why they declined or what they wanted via the message box feature
5. You didn't make offers to any of the 136 other people with copies for trade
Trading is a puzzle, and requires you to profile the recipient before you offer.
You cannot enforce your values on the other person.
Unless you can approach this purely objectively and remove all of your emotion, trading will be a source of endless frustration.
Of course, all of this is IHMO.
I hope you do not take offense to this, since your response was clearly impassioned.
I took the time to write this because I used to be in your shoes when I started, until I figured out how to play the game. Traders must learn to never take anything personally - thick skin is mandatory. Otherwise, they won't last long.