As discussed in these questions regarding shortsshorts, underclothesunderclothes, and nightgownsnightgowns, among others, there are certain restrictions of what one may and may not wear when davening.
I am assuming it's better to wear even a disrespectful form of clothes than to wear no clothes, which is even more disrespectful. Under that assumption, what if someone had two sets of clothes - say, the clothing he slept in and a pair of shorts, neither of which, as discussed in the above questions, are permissible to daven in - and he's stuck in the middle of nowhere and there's no clothing store he can get to before the zman tefillah passes. Which set of clothes is it better for him to daven in? Does he even daven?
(Of course, CYLOR before you embark on a trip to nowheresville, Kentucky without a few sets of clean davening clothes.)