Auditioning to teach lessons

I played an audition one time.  That was for a band program on the south side of Dallas some years ago, but I decided not to teach there.

Yes it is becoming common.  Standard practice - not yet.

I don't do auditions.

I auditioned to teach in my district, contrasting etudes/solos. They explained that since I would be modeling they wanted to insure that my tone, technique etc was compatible with what they are teaching. It wasn't a bad experience.