+1 on this approach. I've been a barefooter for the last 7 years. Countless encounters concerning my unshod state at establishments where there were no postings and/or vague policies. Politely ask to see policy, and adjust behavior accordingly. After about a year or so, I grew weary of having to plead my case and/or take the time to talk to policy makers and now carry flip flops wherever I go...
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