I don't care to see the HTML versions of emails in Gnus, so I have this in my .gnus configuration file:
;; Don't display html inline (setq mm-discouraged-alternatives '("text/html" "text/richtext" "text/enriched") mm-automatic-display (remove "text/html" mm-automatic-display))
Which works nicely for email and news articles. But for rss feeds I would actually like to see the HTML version, with nice links and paragraphs, pictures etc. - so I've set the topic parameters of my rss topic to include this:
((mm-inline-text-html-with-images t) (mm-discouraged-alternatives nil) (mm-automatic-display (union '("text/html") mm-automatic-display)) (mm-w3m-safe-url-regexp nil))
... i.e. no discouraged alternatives and add text/html back into mm-automatic-display. Works as expected. Great!
Gnus is quite configurable when it doesn't just do the right thing out of the box.