The clothing tool so far seems totally functional. I've tried it with many different age groups/lots and haven't glitched yet.
Did I mention that it also uses the new clothing selection interface?
There is one problem with this though and I think it's more to do with Nightlife than the hack.
Prior to installing NL, I used this hack in conjunction with InSIMinator so that I could alter Townies (it really the only reason I use InSIMinator). I would use the 'Career Adjuster' function to make all rewards available and then get the Home Plastic Surgery reward. Then I would use the 'Summoner' function to bring various Townies and NPCs to the lot. Another InSIMinator function allows you to make visiting Sims selectable, so I would do that. With boolprop, I'd boost their Aspiration to Platinum and get then to do the plastic surgery thing. Then I'd use the clothing tool to change their clothes (not with NPCs - just Townies) and set their make up and hair.
In less than a couple of minutes, each of those Townies and NPCs that looked like they were the offspring of John Merrick and had bought their clothes at the local charity shop where given a whole new look.
So, with Nightlife installed (and having to start the game from scratch all over again), I prepared to start doing some more Townie/NPC makeovers. But not so easy! All went well until I used the clothing tool. I selected an outfit for a Townie and clicked on the tick to confirm and it went to the screen to choose the outfit. But their was nothing in the inventory - not even the clothing they had been wearing and the option for choosing between tops, bottoms and full outfits was greyed out. So the Townie ended up walking around naked ... and stayed that way when she turned up next time. I eventually had to use another InSIMinator function to age the Townie to Adult and then drop her back to Teen. She was then dressed in a different Maxis default outfit, but a better one than she had been in originally. Thankfully, the part of the clothing tool that works the same as a mirror for changing appearance, worked fine.
I know JM doesn't support or favour InSIMinator, so I'm not expecting him to look into this particular problem, but it would be nice if someone would create a tool for changing Townie clothing which allows the use of custom clothing. I was disappointed to discover that you can't buy clothes for other people like you could in Hot Date in the original game.