Don't EVER put your suitcase on the bed.
Because your suitcase is way filthier than you think. You wheel it around through airports including the airport bathroom for a carry-on. You wheel it around outside, where it's picking up dirt and, yes, traces of feces.
If you don't believe it, take a Clorox wipe to your suitcase's wheels right now.
And you DON'T want all the bacteria from your bag getting on the bed. Even if it's a hotel bed, those germs can get mixed up in the sheets.
Plus, if it's a hotel bed, there's a chance bedbugs could latch onto your suitcase as well. So keep your bag on the ground or a luggage rack.
(Afar)