Perhaps somewhat stating the obvious. But if they seem to talk about a lot of past acts with different past subs, I'd take that as a sign that their subs didn't hang around long term. And that would lead me to ask why, and if the conclusion I came to matched up with the kind of Dominant that I wanted.

If they're just talking about past acts with one or two maybe I'd view it as different, but it still has a "here, look at my Dom resume" vibe, as opposed to a "how can you and I mesh best" vibe.