If it smells, I bin it.
Most makeup like mascara and eyeliner should only be kept 3 months, brushes (good brushes) i wash with a baby shampoo and air dry.
Sponges and applicators are disposable.
Oh and I refuse to share my makeup- point blank.
i DO NOT share ANY of my makeup. brushes get washed once a week with a clarifying shampoo. my beauty blender gets washed whenever it's used. as far as makeup goes, i toss mascara after three months. anything that has separated, or smells off, gets thrown away instantly.
I wash my brushes twice a week, and wash my foundation brush after every use. I use Philosophy 'Purity' to wash them. Technically this is a face cleanser but I ended up with a large bottle of it and I didn't like it anymore as a cleanser, so I started using it to clean my brushes after it was established as a good product to use for this. I wash off my brushes facing down, tipped into the stream of water to avoid getting the stem wet, which can damage the brush.
I also have an MUF Instant Brush cleaner spray bottle (alcohol-free) which I use as a quick cleaner if I'm using different coloured products and don't want any colour residue transfer.
I don't share make-up but I know you can sanitize it with an alcohol spray. I've seen people selling makeup second-hand (eyeshadow palettes, blushes etc), using this method to clean it, but I still can't bring myself to buy used make-up. I don't like store testers either, even when they're freshly 'sanitized'.
As others have said - I chuck any make-up that looks or smells funky. I've pretty much been living off mascara samples for years (I always get tons of deluxe samples), so they get used-up and tossed very regularly.
I don't share makeup or brushes, I wash brushes in dish soap. If a palette gets all dusty, I wipe it down with a paper towel spritzed in rubbing alcohol.
