Howdy,
Working in an industrial area, (first chemicals, now coal-fired generation) I have taped wirenuts for cleanliness issues. Both areas had a great deal of dust that seemed to get everywhere. I have removed my own tape years later and the connection was still clean. You couldn't tell what color the wires were until the tape was removed.
Sadly in industrial situations there aren't too many applications that don't get "revisited" for equipment removal and such. (We have always reserved wire nuts for lower voltage and for frequently accessed devices.) Everything else gets a more permanent connection (terminal bolts).
