Perhaps a cause of this recent wave of spam is that the message originals show the text of these emails as V0UgQ0FMTEVEIElUIEFUIC4zOCBDRU5UUyBOT1cgSVRTIEFUICQyLjQwISAN CldJVEggQUxPVCBNT1JFIFJPT00gVE8gTU9WRSENCg0KQSBIVUdFIFBSIENB TVBBSUdOIElTIFVOREVSV0FZIEZPUiBGUklEQVlTIFRSQURJTkchISENCkVY UEVDVCBTT01FIFZFUlkgTklDRSBHQUlOUyBUT01NT1JPVyBNT1JOSU5HIElO VE8gTU9OREFZISENCg0KKiogQUNUIFFVSUNLIEFORCBUUkFERSBPVVQgVEhF
whereas we get to see the sales pitch!
Surely gmail's filter could parse the above and recognise it as spam?
I wonder whether they're taking into account the "Report Spam" data on a continuous basis? Given the performance of the spam filter on the specific kind of spam we've been seeing (and tagging) over the last while I'd say they improve the filters in big updates. Not so good :/