(let's face it, I have waaaay more bad habits...but we won't get into all those lol)
When I'm running late (read: every morning) and I don't have time to do my makeup, I just grab my little case and do it in the car... it saves time and occasionally allows me to sleep an extra 5 minutes, meaning it's totally worth it.
Sometimes, it does cause problems-like when it's 468472467 degrees and my eyeliner melts, or when it negative 5695868 degrees and my mascara freezes, but barring those, it's not too bad.
The other day, I was running behind so I did my make up in the car and all was well. Except when I came out to my car after work- My makeup mist which usually looks like this:
Looked like this:
It had pretty much completely melted!