I actually walked out of a Smosh when I had an interview because of their bullshit.
I had class to get to and my appointment was at 1pm.
It wasn't until 2:30 until the guy came back to get me. I had class at 3:30 and had to leave right then. I just stuck around to say this:
"You know, I find it a bit unprofessional for you to make me wait this long to see you. You knew I was going to be here at such and such time and it didn't matter to you. I don't mind waiting a half an hour or so because I know that you sometimes get backed up. But frankly there is hardly anyone in the store and almost two hours is unacceptable. Hopefully the next interview you have will be professional and on time."
I get called the next day by the store manager (I was interviewed by the assistant manager) who asked why I didn't show up. (OH IT WAS FUCKING ON THEN!) I explained what happened, that I did show up, and I had to leave because he kept me waiting so long. I was called back 2 days later and got the job.
The assistant manager made my days there hell until he transferred to another store. Don't worry, I didn't accept it for too long. Eventually I told him to stuff it and frankly, no, I didn't care if I got fired. I was sick of his chauvinistic, racist bullshit. The Store Manager was 150000000% behind me.
So, if they are this unprofessional at an interview, they will be worse later. RUN. If this ever happens again, I will just laugh in their faces if they offer me a job.