Curiously, when I've gone to see National Tours that have come to my town, I've usually seen understudies for the main role, and loved them.
For example:
Didn't see Carly Jibson in Hairspray, saw Keala Settle instead. JOY!
The first time I saw Mamma Mia! I saw Tony Clements as Sam (he was the understudy at the time). Loved his performance! (And then, to sweeten the deal, two years later, I saw him again HEADLINING the role, and got to talk to him at stage door, which was amazing.) But I digress.
Yes, understudies, even if they're a notch below the lead performer (and usually they aren't) they definitely deserve love
Q: What is the most weirdest or funniest thing a fan has asked you?
Joe Flanigan, Stargate Atlantis: When a fan asked me for help with his grammar. I'm available.