I think Rise of the Cybermen and Age of Steel demonstrate an important subrule: Ten will not stick bits of a parallel universe in his mouth. That's why they only had him kissing the crystal, and not Mrs. Moore. I'm assuming he learned that the hard way. There should be fic explaining that, possibly involving a previous Doctor sticking bits of a parallel universe in his mouth with Unfortunate, Hilarious, and/or Sexy results.

You should do a spreadsheet. To show off you skience.