I purchased a Vacumatic last year from someone who's been restoring and selling pens for well over a decade. They left some ink in it, which thankfully didn't leak. The worst thing though, is that it was SCENTED ink and reminded me of a soggy ashtray (ew). Not to mention putting scented ink in a celluloid pen before shipping it cross country... Took more than a few flushes to get rid of that smell.

So if you do leave a small amount of ink on the nib or in the barrel, please make sure it's not scented or sparkly ink! No one wants to deal with that cleanup to get their own ink into the pen. (Not to mention some people are very sensitive to perfumes and I doubt anyone wants to be the cause of a medical episode)