I’m seeing a lot of bass machismo in this thread. As if it’s a given that a.) playing music means playing standards, b.) playing well = being able to play anything, and c.) that throwing random songs at someone is a valid test of musicianship.
I back up a lot of singer-songwriters. I work hard to realize their vision, which sometimes means something more than the most obvious jump-in-and-play-by-ear choices. Their songs aren’t familiar standards, and often quirky in their own way. My attunement is to their individuality, which perhaps means my ear isn’t as well-honed as other players.
I recently had a successful audition with an all-original band, anchored by an incredibly talented singer-songwriter. I showed up ready to play four of their songs, one of which was a song in development which allowed me to demonstrate my original bassline writing skills. If they had broken into a jam or Mustang Sally, I’d have been annoyed: that’s not what I was there for. Different music, different demands, folks.
It's typical TalkBass, the assumption that everyone here should be playing at a certain level and willing to bend over backwards in any situation regardless of their own needs or requirements.
I haven't done a "true" audition for a few years, but I remember the times I did when I was new to the scene around here. Nowadays I get jobs by word of mouth or through networking at higher level jams. I can empathize with some of the players who are just getting their feet wet or getting out there again. Even though I haven't done an audition, per se, in a long time, tonight I've got a bunch of people coming over here, most of whom I've never met, to go over some songs I'm learning for a show in December. I was told by the BL, who recruited me, that "final say" on who gets the chair goes to the drummer, who will be here tonight, but I don't think there's really anyone else on the sidelines waiting to see if I pass muster or not. The BL knows me, knows how I play, and both he and I are confident that the drummer will be happy. That's about as much auditioning as I ever do nowadays.
As for hanging with other players on short notice, I have a show in two weeks and I will likely just show up with a book of my own notes and play, having never met anyone except that BL. I have a high degree of confidence that I can make good decisions on the fly; most common music is painfully predictable. It's mostly blues so not a tough row to hoe.
BUT for the purposes of this thread and the variety of people who are here reading, it's not always that simple and I like to be mindful of the fact that we have beginners here, and people who haven't been exposed to "all the standards" (whatever that means; none of the bands I play with have much repertoire in common). For most people it's intimidating to be asked to do things they haven't prepared for. I was like that for years. I needed a lot of experience to become comfortable doing what I do.
My very first audition in this town was much like what you describe, an originals band, and I had learned their songs from online recordings, walked in, we played through everything without stopping, and when we were finished there was plenty of time on the clock so they asked me if I wanted to play some covers and I said "yes," so we did that. I didn't take it as a challenge, it just seemed that they'd enjoyed playing with me and didn't want me to leave, and I didn't leave for four years. Well, I went home, but you know what I'm saying
Sometimes it's about other stuff, but if you walk in and nail the stuff they asked you to learn you're never going to disappoint anyone, and if you're doing things at the level where improvisation is requested or required you'll probably know that before you ever go in, because they'll tell you.