having now taken a look at the codebase, I can see that most of it is in fact perfectly well suited to such colour highlighting and I'm probably creating a small fuss over nothing; regretting bothering to submit the report now.
two utilities are missing it - start-stop-daemon and update- alternatives, but I don't know whether to bother submitted a patch for that. I should probably take it on good faith that it was thought unnecessary for them, considering the excellent state of this throughout the dpkg source anyway. so going back to the case originally mentioned of the output from when dependency problems exist when trying to perform a purge, the only question is whether this could be enhanced with a colour highlighted error/warn label...
