As a pest control professional, I just had an airbnb customer of mine contact me...his listings have bedbugs.
There is no prevention, only treatment.
As with steam, heat kills everything.
While cleaning, if it can go in a dryer, put in for 45 minutes on high...pillows, throws, area rugs, etc.
They typically live within 5-6 feet of beds, chairs, sofas, etc.
Encasements mean you can see everything.
Evidence includes small blood smears on sheets, so if you see this afterwards, assume your guests brought them in.
Cycle of reproduction is fast and very few products kill eggs regardless of what they say.
Standard treatment includes 2 treatments 10-14 days apart to address eggs hatching.
Treatment includes baseboards, outlets, dressers, nightstands, and if you can, use simple headboards easy to inspect. ..not anything cloth based with and lots of sewn tufts (hiding places they love)
As far as preventive steps; if I were listing, would include treating (as part of cleaning regimen ) bedframes, sofas/chairs and empty dressers/nightstands (whole thing inside and bottom/back with an aerosol product called Bedlam if you can find it.
Seems to be worth the effort if they are going to make you prove treatment before listing again.
Serious enough an issue that when I have inspected for them during my day, first thing when I walk in the door is everything I'm wearing goes in the washer before I go any further.
Treatment cost should be somewhere in the neighborhood of $200/room (rooms with soft furniture, not kitchen, baths, etc.) if you find yourself with an issue.
I am doing one this week for a current customer for $150/room (including both treatments).
I am in the south florida area if you need more information...Joel 9546614978...advice is free.