As for shows that I've walked out of...
I think I've only left one... maybe two.. but only one I can remember. I think it was called Liberty Sings - or America Sings. It was a revue of songs about America and the American experience. If I remember correctly, it originated in Philadelphia - I saw it at the Kennedy Center's Terrace Theatre in Washington, DC. It was OK. I was with a friend. It was my friend who wanted to leave at intermission. I had paid good money for the ticket, I wanted to stay. He wanted to leave. He drove, so.. But I didn't mind leaving, so..
Otherwise, I stick it out. The one show I was really tempted to walk out of was Shogun - The Musical during it's pre-Broadway run at the Kennedy Center. If people thought it was bad when it was in NYC.. WHOA!! I truly felt bad for some of those actors on stage - and I knew some of them! And the leading man, Peter Karrie, I believe, was just not up to snuff. -He was replaced by Peter Casnoff in NYC - whom I would have liked to see. The whole show was one big collective rip-off of all the mega-musicals that came before it. At least June Angela got a Tony nom for her work.
*Funny thing, whenever I pay full-price for something at the Kennedy Center - play, musical, concert, recital , etc. - it usually turns out to be a less than thrilling experience. However, the comps, half-pricers and gift tix, tend be very pleasant surprises.