The :order => "created_at ASC" in the acts_as_commentable definition in lib/acts_as_commentable.rb overrides the "created_at DESC" in the :recent named scope, generating a query like "ORDER BY created_at ASC, created_at DESC".

This should be reproducible by calling #comments.recent on any commentable model with multiple comments.

Should be resolvable by removing the :order param in the acts_as_commentable definition unless I'm overlooking something. Glad to provide a pull request if you'd like, but likely not worth it given the simplicity of the fix.