My practice is, if you get a high end rifle with a good scope, take
it off. Guys that buy this type of rifle have their own ideas about
scope. If you get a off the rack 700 or 70 ect with a good scope
peel it and replace with mid range price scope. If you get one of
the entry level rifles with a good scope ( which is rare) replace
with a cheap 3x9 and send that piggy to market. There are
exceptions to this, a specialized rifle with matching purpose
scope may be better sold as a unit. This practice works good if
you do a lot of dealing and have a few scopes on hand to swap
out. Not so good if you have to buy scopes. I have always been
leery of buying used scopes unless hi end backed by guarantee.