@Sarah3679 If bedding is totally ruined because a guest was really disrespectful, then charging for the damage might be in order, but bodily fluids on bedding is totally normal and just something hosts have to deal with.
You will become adept over time at learning how to remove most stains, and there are threads here you can search out, not to mention tons of info that can be googled, on how to remove almost any kind of stain.
Something else to consider when you host is not to purchase "sets" of anything that would need to be replaced simply because one piece of a set got damaged beyond repair. That goes for dishes, towels and linens. So you either buy all white sheets and towels, or decide on a color scheme like "greys and blues", so you can buy another towel or two as needed and still have it look intentional and coordinated. Or if the listing decor lends itself to such things, bedding can be mix and match. I have a few colors of things that go well together and with my decor, so I might use a burgundy fitted sheet, a grey top sheet, and patterned pillowcases that tie in both colors.
With dishes, look for things which you can replace by the piece (like plain white dishware from Ikea) and always have a few extras on hand, so you don't have to run out right away looking for more, because dishes inevitably get broken or chipped, even by respectful guests.
And if you set aside a certain amount from your nightly fees and put it in a special fund for replacing things like this, it will stress you out less when something gets irretreivably damaged, and you won't have the dilemma of "Is charging for this petty and/or will it lead the guest to leave a bad review?"
And a piece of glass or plexiglass on wood table tops can save your furniture from getting stained. You might try laying a cloth soaked in baking soda and vinegar over that coffee stain for awhile to see if that removes it.