quick question. :)

Stipulations in GA descriptions don't count.
You can ask for someone to agree to delete a GA if the key doesn't work but they are no obliged to.
So, you owe them a working key/game or have a "not received" strike in your account.

There are special groups for this. For example, [Group] Delete giveaway if key is not working. (of course you can't guarantee 100% that people there will not demand the game but it's like 1% possibility or even less...)
Also you can drop the key on other threads with some puzzle for bots to not get it... For example, Orphan keys drop thread

There are currently three groups that you can use, where winners are expected to agree to the deletion of a giveaway for a bad key. They are:

• Lootboy SG
• Delete giveaway if key is not working
• Bundle Oldies