I have been doing a test for a few weeks now on the plastic inside the bed. I use the Honda Spray cleaner/ Polish on my truck. Yes Paint, wheels, and plastic! Trust me guys, your mouth will drop once you use it. Anyway When I got done detailing my X I had the same wet microfiber cloth from the polish and I used it on the bed. I didn't wipe the bottom of the bed, just sides, tailgate, and front bed. Over the last few weeks I haven't touched it with anything. I wash the truck and just hose it all down to get ride of the crap.
Tonight I washed the truck again, I haven't driven it for about 4 days and it has been raining and sunny. So there is pollen in the air and everything else so the truck looked pretty bad. Being the fastest truck out of the 3 for getting dirty, I had to wash it up before taking it tonight.
I'll get to the point, The places where I just wiped with the towel is still very clean and the water beads up like the rest of the X. I got home and looked in the bed and the sides were like brand new, bottom however was still dirty looking. It is in no way slippery or nasty feeling. I'll take a pic tomorrow of the difference so you can see before I clean the bottom.
So The Honda spray cleaner/ polish works very well for me and my X. (it beads up so much the soap even has a hard time staying on)
But it is hard to find because it is discontinued. But I have a couple of cases.