What a ridiculous thing to say, boo-freakin-hoo. That's what business is, dealing with customers, interacting with customers/making customers feel welcome whether you make a sale or not. People are always trying to get the best deals possible, that's life. You/i and everyone here does it when buying domains and so does everyone else when it comes to life in general.
But let me get this right, when the shoe is on the other foot and it comes to SELLING domains, things change, it's all me, me, me, i don't want anyone haggling me, i can't cope, i don't have time to say no, here's an idea lets charge people to send enquiries further improve my bank balance, because the world revolves around me right?
What happens if a person sends a lowball offer with every intention of spending big, I've done that before in business, why? Because that is business, if a person doesn't like that side, they shouldn't be in business, simple as.