Eh. I'll admit that nutrition might be not fully essential, but I wasn't delivering a daily dose of salt about that. I was the one getting irked about the possibility that the filthy clothes thing might ONLY serve to add another useless morale effect, along with the equally-useless deterrant to wearing zombie drops.
Zombie clothing already tends to be in utterly useless condition. Compared to repairs, the added hassle of cleaning it is not a big detriment to how readily you can use it. Hence my question: did they at least do the smart thing and add a higher risk of infection when filthy?