The whole issue of "What songs do we play, and how do we choose them" is a never-ending discussion with no right or wrong, just a lot of strong emotions.
I have seen cover bands reach goals and succeed with nothing but deep cuts and B-sides, personal favorites, obscure live versions and covers of covers of covers that few have ever heard before.
On the other extreme, cover bands play it very safe and target certain venues/clients/audiences and compete with similar bands with nothing but faithfully-executed well-known pop/rock/disco/funk/country standards and bonafide hits.
Sometimes the BL retains "creative control" and picks all or the majority of song titles and versions. Sometimes its a more democratic process.
I don't think it's wrong to ask a BL how his project determines its playlist during the interview, but to make judgment calls and criticisms right off the bat is almost never a good idea. Like entering any committed relationship, you either accept it as-is and jump in head first with optimism, or you politely and professionally decline without comment. And remember: What you see at the onset may be as good as it ever gets. If you join, give it some time so you can assimilate and prove your worth and loyalty. Then, when sufficient time has passed, if you think things could improve, start to diplomatically interject your philosophy about the playlist, song selection, how to target desirable venues/clients/audiences and better compete in your market, etc.