Pencil Marking On Reverse Of Mnh Stamps

I have from time to time encountered MNH stamps with the Scott number written in pencil on the back of stamps. I have been avoiding these stamps because I feel that it detracts from the pristine nature of these items. Can anyone tell me if pencil marks reduce the value and collectability of MNH stamps.

Stamp dealers used to do that quite often, and it usually does take something off the value of the stamp. In my opinion, when the stamp is common, it does not usually matter a whole lot. Sometimes you can actually get initials on the back from well known dealers or collectors that will actually raise the value of the stamp. So, there it is in my book, the old really definitive, SOMETIMES. That stamp comes from a great set of stamps though .

I avoid them as well. But sometimes sellers don't mention it, just listing the stamp as MNH, then it arrives with pencil on the back

Thanks for the feedback regarding pencil marks. I will be doing everything to avoid acquiring MNH stamps with same. Regards Mike