Well, ive only been practicing ployamory since January and havent been lucky enough to have gotten w a bio woman (cis-gendered, whatever, there isnt a good term), and so havent had to think about dams, but I'm with Mono, i would hate to eat a woman w latex in between. Well, I wouldnt *hate* it per se, but it wouldnt be ideal, that's for sure.
I use condoms for intercourse (vag and anal), but dont use a condom for oral. My primary and i are fluid bonded and dont use protection (and i am post menopausal and dont need to worry about birth control). I'd been mono for 34 yrs and she had been (in practice, not philosophy) for 5... and the last 2 yrs of her prev relationship, they'd stopped having sex. M is poly in practice tho and always used safer sex when she was practicing. She gets tested every 6 mos as part of her gender transitioning... Ive never been.
Maybe it's terrible to give oral w/o a condom on the penis, but from what I read, risks are low... i would watch out for herpes lesions of course.