I uploaded three images of screenshots made at the exact same time to snaggy:
http://snag.gy/OSvIR.jpg (001)
http://snag.gy/9hnnV.jpg (002)
http://snag.gy/DyPlE.jpg (003)
001 shows my Feedback section - as you can see, there are two comments marked as spam, no pending comments.
002 shows my wp_posts datatable - please notice the last entry there, which shows a spam marked entry coming from the contact form and is not listed in the Feedback section
003 shows my wp_postmeta datatable - please notice the last three entries belonging to the spam marked entry coming from the contact form
Obviously, spam marked comments coming from the cotact form (which happens about 2-10 times a day) don't make it into my Feedback section and remain untouched when I click "Empty Spam" there.