1937 series notes question

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I have been checking out eBay listings for 1937 series notes (mostly EF condition). What I have noticed is that there seems to be a greater demand for notes that appear original. Notes that have damaged edges or corners and with soiling but with brighter colors generate more interest than notes that appear clean and flat but also somewhat dull looking. Am I right to assume that notes in these series are often washed and pressed to improve their appearance, and buyers try to avoid such notes?

Here are scans from some eBay listings.

Notes that appear original:
http://i.ebayimg.com/t/1937-20-TWENTY-DOLLARS-BANK-CANADA-NOTE-GORDON-TOWERS-/00/s/NjI4WDEyNTY=/$(KGrHqNHJDUE63ZSBeO)BPgiy7sDTw~~60_58.JPG

http://i.ebayimg.com/t/Strong-1937-Bank-Canada-10-banknote-Coyne-Towers-BC-24c-EF-/00/s/Nzk4WDE2MDA=/$(KGrHqJ,!rEE88gWlgGtBPflOGlU9!~~60_57.JPG

http://i.ebayimg.com/t/Strong-1937-Bank-Canada-20-banknote-Gordon-Towers-BC-25b-EF-AU-/00/s/ODEwWDE2MDA=/$(KGrHqZHJFcE9196!QkbBPflRH0FK!~~60_57.JPG

http://i.ebayimg.com/t/1937-20-Bank-Note-Canada-Canadian-Bill-Old-Paper-Money-/00/s/ODk5WDkxNA==/$(KGrHqJ,!lQE9Hqo7i0YBPeMK1cHl!~~60_1.JPG

Notes that may be washed and pressed:
http://i.ebayimg.com/t/1937-BANK-OF-CANADA-20-00-B-E-6507889-Go-To-1658-/00/s/NzU2WDE2MDA=/$(KGrHqFHJEQE88dE)+y,BPgRZFQp1g~~60_1.JPG

http://i.ebayimg.com/t/1937-BANK-OF-CANADA-20-00-J-E-1430167-Co-To-1664-/00/s/NDIzWDg4Ng==/$(KGrHqNHJDME91Hu,!11BPglDpVP3Q~~60_12.JPG

http://i.ebayimg.com/t/1937-BANK-CANADA-KGVI-20-Gordon-Towers-XF-/00/s/NDc4WDEwMDM=/$(KGrHqFHJDEE9(0vl8G1BPhwr7FR0!~~60_57.JPG

How can you tell these have been washed/pressed from a scan? 

Also, when it comes to scans, you can usually assess condition better from the back side of the note vs. the front.