JabRef 3.8.1
windows 7 6.1 amd64
Java 1.8.0_66

I noticed after an errorneous biber compilation that cleaning the % sign is not without risk: I found in the bib-file doublebackslashed % (\\%) which do help since they have the meaning of a new line and and a % sign. Obviously the cleaning does not discriminate between \% and %.

Steps to reproduce:

1. a bibentry with a % sign in the abstract like PMID 27151464
2. run Quality > Cleanup Entries ( with abstract: Latex cleanup added) twice

I may be wrong since a cannot reproduce this, but I know for sure that yesterday I found the backslash doubled and I did not anything but the cleanup.

BTW I noted also that between the % sign and the following dot a misplaced white space was added.

Perhaps someone can reproduce this issue.