Funnier by-the-numbers version.
I used to do this shit all the time to varying degrees. Shooters would come in, drop off their files, or in the old days, film, and I'd fix up the issues.
Good lighting and an excellent make-up artist go a long way. When I do DJ shoots, it doesn't matter as much, DJs and musicians are supposed to look banged up. With girls, whole 'nother story. I either request they pay for a good MUA, or they pay me extra to take care of it later. I'm lazy, so I do prefer to have it done right the first time.
Though I've been fortunate enough that the girls I've shot tend to know what their doing when applying make-up, or just naturally look good. There's this one girl I snap a photo of a lot lately, and she needs little to no work. She looks good at 6 AM.