This comment on dcubed, by someone apparently replying to himself, flummoxed me momentarily: "Can you please stop using my id. I thought you had stopped after my last appeal, but you have showed up agin."
Had this poster given out his password to an unpleasant character? Why didn't he just change it? Or is blogger trivially crackable? Can I log in as anyone I like?
Then I realised that while I can't do that, I can impersonate anyone I like, and the results are indistinguishable from genuine comments. (I'm not telling how, but it's trivial.) While one can forge email headers, the results can be detected by the savvy; here, there seems no way to do so, unless one has access to Google's internal logs. There seems, also, no way to disable this "feature", short of disabling anonymous comments totally.
Blogger sucks. It sucks in many, many ways (one of these days I shall count the ways), but this one is the most egregious I've seen so far.