@Mark1340 I generally think it's pretty disrespectful to ask for discounts. It's basically saying that your place isn't worth what you are charging. And most posts I've read here on the forum over time lean heavily towards the guests who ask for discounts turning out to be bad guests in other ways.
However, as another poster mentioned, there are some cultures where you're considered foolish if you don't try to get a bargain on just about anything. And some individuals outside those cultures who were just taught to always try to get the best deal possible.
I also think it depends somewhat on the price point of the listing. If it's an entire home that sleeps 8 and rents for $400/night with a cleaning fee, and the guests, who have a string of good reviews saying they left the place immaculate, etc., want to book for a week, I can see them trying to get a bit of a discount.
But if it's a private room for 1 or 2 in someone's home, with use of shared kitchen, and other common spaces, that's listed at $25/night, the host is making such a small profit, that asking for a discount is pretty rude.