Ian, at least you can be fairly sure he's not a heroin addict. As I understand it, they can't stand any sort of bright light. In the druggie dump we renovated a couple of years ago, all the light bulbs (except one or two) had been removed (presumably so they couldn't be accidentally turned on). My enquiries led me to the above explanation.
As an aside, it sounds like our druggie wasn't as well off as yours Ian, as the level of squalor inside this place was unimaginable. And the only TVs were the broken ones holding up doors that had been ripped off the hinges
Needless to say we got it for a 'good' price and made it into a little palace
Interestingly, $5k in cash in a bag was part of the settlement deal - for the next purchase presumably
Cheers,