They never guarantee it to come back as a straight grade. They will do as much as they can to conserve the coin, in turn improving the aesthetics and to act as a preventative, BUT depending on the measures they take, the grader may or may not deem it "cleaned". I've seen it go both ways.
IMO, if there's a higher chance of it already getting a DETAILS grade, then it wouldn't hurt to do the conservation, or if there is too much distracting staining, residue, etc. If it doesn't have any of the above and will most likely straight grade, then I'd say leave it be.
You just never know how it will turn out, being they will not share how they will conserve the coin, you have to hope and trust their process and that's about it.
Edited by Ty2020b
08/04/2020 2:31 pm