Charlotte Bill's "confusing fall warbler" reminds me of a note in Roger 
Tory Peterson's account of Pine Warbler in the 1947 edition of his 
field guide. He quotes a colleague, " a museum tray of Pine Warblers 
looks like a catch-all for the museum's ratty, discarded Warbler skins. 
"
RTP also said in the same book, " If at the end of ten years of field 
work you can say you know the fall Warblers you are doing well." He was 
an optimist.

(Yeah, the book is old. I bought it from paper route money.)

Bob Budliger