A few minutes ago, an answer appeared to one of my questions, blatantly not an answer, but somehow it wasn't detected and filtered by SE itself. Also, the user has been posting this on other questions too. Is this a bug in the spam filters or not meant to be detected?
That doesn't seem to be spam to me, and definitely it doesn't have enough of anything to be detected as spam.
Although we don't know the exact way spam is detected, very obvious spam still gets to the site and is detected by one of the tools built by community members, like SmokeDetector. That image doesn't have any text to match against, and the picture isn't spam either.
I would flag this post as very low quality or abusive.