When you do this, the mascara dries out faster and you get bacteria in there easier.
When you take mascara, spin around with the brush instead!
Do not lend mascara or share with someone, bacteria spreads fast and you can get eye infections.
This is a little test i did a year ago, my all time favorite is the colossal, and I've tried quite a few mascaras, i always come back to colossal! ;D (and its yellow.. my favorite color!)