If you buy them for anything over face, which you do and everyone who buys altered cents does, why would you spend them for face? Of coarse you could slip them past someone who doesn't notice they are altered, or would accept them for face value in a transaction who doesn't know or care otherwise... or even cash them in to a bank if they are in a roll.
That's not what I'm asking.. The simple question is, can they be used yes or no? Believe me, I know that I would never spend them, we don't even have to go there
The answer is yes the can be 'used' and no they cannot be 'used' if some rejects them based on the alteration and knowing the law. Per the examples I noted you might be able to 'use' them... however I didn't cite any of the legal issues for which it is generally illegal to deface a coin and try to spend it. BNB, the topic has been addressed here, there and everywhere. Try a search like, 'is it illegal to deface a coin?' do some reading then you'll know. No use to really reiterate every nuance in your thread. If all you wanted was a yes/no, you should ask Google.
The short answer is "yes. In a bit more detail... Coins, to include defaced American coinage like hobo nickels, are not legal tender, so it is up to the person/entity who is being offered the coin as payment of a debt that decides if they are "used" or not. Said another way, there is no problem in trying to use them but they may or may not be accepted. Respectfully...Mike