Or your replaceable derailleur hanger! Or spokes. Or uneven shift housing ends. Or any number of other annoying creak causes!

To the OP:

The best way to restore frame bottom bracket threads is to find a small (1 1/2" I think) radial wire brush from the hardware store for your drill. A long-time frame builder friend suggested this to me years ago. This will return the threads to pristine shape. Often better than when the bike was built. It will remove any rust, overspray or gunk in the threads, leaving them perfect for threading in replacement BB cups.