So long as you use protection, you'll be safe from most things. Remember, you don't know *any* of these women. Any prostitute could've been a barebacker in her old country or before she started using Adultwork to sell herself. A lot of them will do bareback if paid an amount so ridiculously high to make ti worth the risk - and there's people from places like the Arab Gulf who are willing to pay. Every girl who has done porn barebacks - they get tested once a month but not every day. And that's not even getting started on their personal life. You don't know whether they do drugs, or are promiscuous in their personal life, or have/have had various other bareback sexual arrangements with other individuals who may or may not be at-risk of sexual transmitted diseases, whether that's pimps, boyfriends, landlords, whatever, at any time in their personal history. Also, a lot of these girls have manipulative tendencies, mental disorders or financial desperation so will try to deceive you and it's important to be wary of that and approach punting as a transaction rather than developing any level of emotional attachment or sympathy.
With OWO, you are taking a risk. The act itself is fairly low risk, so you may decide it is worth it personally, but it is there. I think it's worth it with certain girls who are particularly talented, but I wouldn't do it with every girl I've punted. Nowadays I try to avoid RO simply because I feel I get nothing out of it and thus exposing myself to that risk is unnecessary.