Avoid bed-liner like the plague, it will always be dirty.
I had the interior of my 48 Willys wet sanded down with 400 grit, getting ready to spray body color on the floor.
My wife said "the first time the granddaughters ride in that they are going to scratch the paint, and you will throw a fit" I thought about, yes she is probably right, so I sanded it down with 80 grit, bought an under-coating gun and sprayed bed-liner.
I hate that bed liner crap, it always looks dirty, it is impossible to clean.
That is the last time I listen to the wife.