[Andrew Hackard]

If a monster doesn't allow you to Run Away at all, then there's no attempt that will automatically succeed or fail. (But some Items will allow you to try to escape even from monsters that don't normally allow a try; they will explicitly say you can roll even from those monsters.)

If you're under a Curse or Bad Stuff that means you automatically fail your next attempt, you can't use something else to make that attempt succeed (unless, as above, it says it can even supersede automatic failure -- Magic Lamp, for instance, or Tomb Dust, as you mentioned).

You can't use a Hireling to escape an automatic failure. You also can't use an automatic success to counteract an automatic failure, unless the auto-success says so; automatic failure trumps automatic success.

A monster that won't even pursue you never causes a Run Away attempt in the first place, so it doesn't trigger an automatic failure effect -- you're still stuck with it. However, if another card (such as Flask of Glue) counteracts the "will not pursue" clause, then your automatic failure kicks in.