www.alphadictionary.com

Anyone know a word - I haven’t had any luck with reverse dictionaries - for ‘deliberate mispronunciation,’ - as for comedic or emotive effect? (Or ‘deliberate use of incorrect grammar,’ either.)
I’m thinking of some very effective examples.
I think such rhetorical devices may go back a long way, and might have had labels attached.

It's not exact, but spoonerism comes to mind. The original wasn't intentional, but nearly anything you see nowadays called one, is.

Also, is there a word for deliberate misspelling in commercial names, e.g. 'Quik Kleen', 'Eezi Stick', '[Baked] Beanz', 'Lo Cost'?

I forgot all about the other word for word mangling; malapropism (here, here, and here).

Spoonerism on the Agora can be found here and here.

As to Audiendus' query, I've seen adspeak used. Does that work?

As to Audiendus' query, I've seen adspeak used. Does that work?

'Adspeak' is a more general term, referring to advertising jargon, clichés etc.

But I have found the answer! Wikipedia calls deliberate misspelling 'sensational spelling':

http://en.wikipedia.org/wiki/Sensational_spelling

That is quite interesting, but we’re still missing its vocal cousin. Closer, but no cigars yet. I’ve just found this ‘obsolete’ word in the OED: missounding, ‘Erroneous or uneuphonious sounding (of music, words, etc.),’ which could include intentional application.

It's not exact, but spoonerism comes to mind. The original wasn't intentional, but nearly anything you see nowadays called one, is.

I’m remembering the very clever Two Ronnies, from BBC television.
Wordplay-based humor I always found so much funnier than Monty Python, and way better than Rowan Atkinson or Benny Hill. They got off hilarious routines based on ‘naughty’ spoonerisms. They can be seen on YouTube.