@Sam397 I also use pump containers. I buy big bottles of liquid soap at Costco (there's lots of places you could source them, though), and just top them up between guests. It seems "fresh" to guests if it's full, rather than half full. I'll bet if you'd refilled that shampoo bottle so it was full instead of half-full, and wiped it down good so it looked new, that guest would never have had any complaint. Or you could get those dispensers that go on the shower wall, which personally I don't like the look of, but that's just me.
But guests leave lots of products behind, and I hate waste. If what they leave is at least half full, I have a basket where I put all that stuff. It's an ever-revolving selection, that might have sunscreen, shampoo, shaving foam in it one month and a slightly different selection the next. But what I do with all those containers is wipe them down with antibacterial wipes, making sure they're not gunky around the lids. I point out the basket to guests, telling them to use anything they want from there, that it's things people leave behind, and that I sterilize all of it. I notice that plenty of guests make use of things in there.
But I'd never leave something that just has a bit of product left in it (I'll use it up myself if I can) or anything anyone touches to their body, like a roll-on deodorant or a used tube of toothpaste that people smear ther toothbrush across..