Redpepper, I'm really confused by your response to this... It seems like she's asking a really heartfelt question here... What are you trying to get at with this reponse?
I've been in a similar situation in the past... Choking used to really bother me. If someone tried to do it to me, I'd tweak. If I saw my partner do it to someone else, I'd tweak... even if it was perfectly consentual. I could handle seeing a lot of things, but that was one that would almost immediately trigger an anxiety attack if I saw. (For reasons I can't explain, choking no longer bothers me... I wish I had the insight to know why, but I don't).
I think the best thing you can do is be honest with your partners. If you find certain behaviors and acts distressing and triggering, by all means... speak up. If you don't, you're going to end up living in fear of seeing something you don't want to and eventually that's going to lead to resentment. Telling your partners means you can sit down and figure out what the best way to resolve the issue is.
Things that I might ask myself in a situation like this is:
"Why does this bother me?"
"Are there limitations that I could live with without restricting their behavior?"
"Is this something that I can be okay with in time?"
"Would having your partners take a precaution like locking the door so you can't accidently walk in on something you don't want to see ease your mind? Or maybe asking them not to discuss their BDSM activities around you? Or only doing these sorts of activities when they know you're not going to be at home?"
I tend to think in polyamory there tends to be a culture of openness.... and assumption that you ought to be open to anything and everything and if you're not then you're not poly enough... but the reality is, we all have our limitations and the things that bother us. If you're not okay with it, you're not okay with it.... and that's perfectly fine and acceptable. It's okay to have limits and guidelines to make you feel comfortable.... and maybe in time, you might become more okay with it... or maybe you won't... everyone's different.