When painted on cigars, diluted petroleum jelly is "oily to the touch" and can "leaving an oily residue on the fingertips." Some 'vintage' cigars were infamous for leeching oils (not plume) when stored for a few years. Coincidence?

Note that I am not saying that using a bethune or painting cigars is a bad thing. Sometimes a cheap cigar that smokes great gets a little help - sometimes a lot of help. Sometimes a great cigar gets a little help - Opus X wrappers get stored in sherry or port barrels IIRC.