I will allow my clients to use poppers BUT?
I control the bottle so they don't take too much, you can tell when they are heading that way as their lips start to get little purple tinged around the edges, if they continue they will turn blue and start talking gibberish, continue further and they will faint from lack of oxygen to the brain. So I control them, I hold the bottle while they sniff them.
I no longer allow guys to pour a little onto a tissue to sniff when they feel like it, the above tends not to happen when on a tissue but putting it onto a tissue puts it onto a slow release into the air which means i can then smell it after several minutes even with the patio door to my bedroom open, I got slightly lightheaded and won't be making that mistake again.
I think the problems come when you allow the guy to lay there with the bottle in their hand, they just keep on sniffing, if you control it then the issues I described in the first part won't arise, if they don't like it then thats tough, its my rules or no poppers.