I store all my funnels in a clear plastic bag. It's the only way to keep dirt off them. If you hang them up, the oil resdue attracts dirt.
The only funnels not stored in the 'bag' is my sand blaster funnels. I sure do not want to use a funnel exposed to glass beads for motor oil!
I have 2, one cut off to fill engine oil, one not cut for transmissions or anything with a full tube. I store them on a screw in the wall (hole in the longer funnel, cut off funnel just goes in the longer one). They drain into a catch can I mounted on the wall too. When I need to use one I clean it with brake clean first since they do attract all the garage dust.
There are nice funnel storage solutions out there. I know the tools trucks sell funnel buddies, lisle or someone more reasonable probably sells them as well. They contain the fluid remnants and also shield the top so your funnels don't collect the garage dirt.
At work the coffee mess uses the big plastic containers of Folger's coffee. They throw them in the recycling when empty. I dumpster dive and took one which fits a bunch of funnels, and has a nice lid thats easy on/off.
I bought one a long time ago that has a lid and a cap on the end to keep dirt out while not in use. I lost the little end cap so I keep it in an old 12 quart T-fal pan with a few used socks so it can drain into those a long with a couple other funnels I use to drain old oil into my storage can, no worry about them getting dirty.