Depends somewhat on the funnel.

I had this same dilemma a little while back when I made a spice rack for my dad. The funnel I had was a little silicone one (it was an effective size for a small spice bottle, whereas my larger plastic one was too big and I'd have probably knocked everything over using it).

The silicone one did the job, but I guess because of static electricity, it kept an awful lot of particles of herbs/spices stuck to it each and every time.

So that meant giving it a quick wash and a dry about 24 times whilst filling all the bottles. Definitely a lot more time consuming than I anticipated.