Hypothetically speaking, If you show up to a shoot with a pimple, is that awful? Or if you have a mole or scar or anything? What are you experiences or thoughts?

One on hand: it's your job to take care of your skin and look the best you can.  On the other hand: a pimple isn't the end of the world.  A model and I were just discussing this, and we came to the agreement that we both understand models are human and break out once in a while or just have bad days.  That much is understandable and any team member who can't deal with that is a douche.  BUT, there are those models whose bad skin/appearance can be connected to things like staying out all night and getting shit-faced at the bar, or showing up on set with In-And-Out burgers and Mt. Dew.  That is unacceptable as it can easily be avoided.

if the purpose of the shoot is to get a handful of portfolio images it's a non-issue (at least for me). a little photoshop can take care of many skin issues and i rarely get someone with perfect skin. if it's a shoot where hundreds of images need to be generated then maybe a MUA can cover it up.

A pimple is nothing. A bad acne, a big scar or a large tattoo is often too much work to deal with if I'm retouching a lot of images from a shoot. In that case I'd find another model.

How flawed? How blemished?

A pimple? No biggie.
Twenty? Probably gonna hurt your career if this is something that happens often.

I have a scar, rarely noticed. If I had a giant one.. this would probably just change the kind of career I would be attempting to have in modelling.

Just to add on to what's already been said-

it depends whether it works for you or not, whatever the "flaw" is. Some of my greatest flaws have actually turned out to be assets. Then again, I'm in the art world, not the commercial/fashion world.

no big deal..just rest well and dont look tired

A pimple or two probably don't matter. I get pimples&i look very different without makeup on. But; what I think is important is that they cover easily with makeup. If you do get them, don't irritate them, try to find a good blemish remover. Mine works overnight(-:

I get the occasional breakout... it only really consists of two pimples at most at one time, though. It's usually related to my hormones and what time of the month I'm at (though no predictable pattern for me, unfortunately). I do my best to makeup over it and apologize profusely to the photographer for the trouble, but it's never been an issue... and I'm always invited back to shoot again, so I know it's not just something they're saying.

My worst breakouts are when I'm traveling... I have to either shoot everything within a week when I first arrive in California from the Midwest, or wait a week or two for my face to breakout then heal. Something about the air, I guess.

Being new to this, I didn't know how I stacked up against other models.  But now I feel much better! Thanks for your input!