Have been seeing the same thing here as well. With spam messages coming through as normal mail.

I have also been having any messages that are replies to messages I send being diverted to my spam folder randomly. It is happening on both my personal gmail account and on a business account.

It seems lately Google has really been less focused on the core components that made them successful in the first place. I have found their search results seem to be returning more spam sites than before. My vote is to get Matt Cutts to come back and start cleaning up spam again :)