Chosid – “In Chabad it used to be acceptable to wear colored shirts, because it was assumed that bochurim we’re penimiyus and didn’t care either way. ”
I don’t believe there is any picture of a Rebbe, Rosh Yeshiva or Rav in Chabad that wore a colored shirt.
Bochurim in Russia, where getting food was a challenge due to poverty or in the USA during Depression would wear whatever shirt they could financially get their hands on. It’s not likethey were shopping in Macy’s or Woolworth and picked the blue or gray designer shirts over the white ones (with French Cuffs – no less).
The same probably applied to all bochurim in both the Old Country (Hungary, Lita, Poland etc) and in America.
The term “penimiyus” vs “chitzoniyus” is misused when applied to clothing, shaving, peyos etc. (reminds me of the non-observant Jew that claims he is a Jew “at heart” – a pnimi!).
A chitzon is someone that does mitzvos only “on the outside” without “internalizing” (in pnimiyus) that he is connecting to Hashem and doing His rotzon.
The conduct and behavior of a chitzon and a pnimi are basically identical except when qualifying the impact of the conduct on the individual.