A trick for this is to occasionally wear two of the same shirt, one over the other, and then at some point get "too hot" and remove one of them to reveal the identical shirt underneath.

Then really lean into it by getting a coat that has a print of what you look like with that shirt on the outside. Dedicate one of the large pockets of a backpack to "emergency" shirts (and use them, eg if you get too sweaty or spill some blood on it). Invite people over and "forget" to put the pile of folded copies of that shirt away. Then each visit, add another pile, until people start questioning whether they are for you or to sell. Vaccuum seal some of those piles and ask friends if you can leave one package at their place in case your place burns down or gets burgled. Start making cheesy jokes about "in my vestments/investmenst".

At this point, you should be able to get away with occasionally wearing the same shirt twice without anyone even guessing that you're wearing a dirty shirt. Because you're the crazy shirt guy that everyone knows has more copies of that shirt than most people have clothes in general.

Oh also, if you ever accidentally rip your shirt, say "aw man, that was my favourite shirt!"

We do laundry every two weeks, so I have 16 copies of a shirt I like (2 extra, just in case), 6 sets of the same pants, 16 of the same underwear, same for pairs of socks. Yes, I'm at least a little autistic, how'd you guess?

Why? Because you always wear the same one? As someone who basically has been wearing the same 5 clothes for summer and winter for 20 years I really don't want to know what people think if thats the case.

The upside is: even if you're wearing a dirty t-shirt, people know you have multiples, so there's plausible deniability.