Umbran said:
Whether or not they care we cannot guess with confidence. But not know? Unless the potential contestant is actively hiding it, I don't find that credible. Generally, it'd be right there in the resume or application, and probably available with a quick Google search. Not knowing would qualify as, "falling down on the job" I think.
I cannot say much (
http://www.enworld.org/showthread.php?t=198025 ). So I will speak from just general experience as best I can.
Applications do not necessary ever ask questions like "have you ever done any performing". And unless you are a full time actor, the job questions they may ask are probably about your full-time job and current employer, and past full-time or primary jobs.
Nor are they necessarily personally doing Google searches on people themselves (Producers probably don't have the time commitment to be personally researching dozens of applicants). They might hire an outside background checking company (like any other company might do), and they would probably look for things like criminal background, mental instability, and that sort of stuff - things relevant to the safety of the participants.
Like I said, you're assuming they care if you have any performing in your background. I am not sure that is a good assumption. I am sure they care if you come across well, if you are engaging, if viewers will be interested in watching you, and if you come across as real, and if you will be a pain in the ass to work with. The kinds of things that are actually relevant to the show. Whether or not you were in a commercial or some plays or a singer or some kind of performing hobby at some point in your life is not really all that relevant to a show. It doesn't make you a less "real" participant, because if you "feel" like a performer to them they probably won't pick you.
Anyway, my point is that there is not necessarily a causal connection between having some performing background and being cast on a reality show. I think it can be helpful because the skills a performer has may help them impress people in an audition. But I don't think people are cast specifically because they have a known performing background.