Clean your funnel before pouring new oil?

[Craig in Canada]

I have a large throat rectangular funnel for doing fills, just to speed things up while reducing the chance of dribbles. I may also use it for transferring oil from 5gal pails to 1gal bottles, or even used oil from my collection tank into some sort of bottle to take to the depot (rare, since the depot will dump and return my collection tank). I wipe it out with a paper towel after use and I store it with a paper towel shoved in the neck to absorb any dribbles. Before use I just make sure there's no particulate on it and fire away, as long as it was used for some kind of petrochemical beforehand (not battery electrolyte or something).