Ha, this exact issue bit us in the ass a few months ago. We were working on some streaming Twitter utilities (put in a username and we fire off some events if a mention or a RT of them occurs) and just to test the scalability of our services we entered Justin Bieber. Well one of his tweets got over 100 RTs fairly quickly and we weren't expecting a string to come back. Long story short, it solidly fucked up our event queueing/processing pipeline and brought some of our servers to their knees.
"Well, we got a string instead of an integer and yada yada yada, our network almost collapsed."
That's a pretty big "yada yada yada" you left out. I am going to assume there's a legit reason why getting a string back instead of another type of reason crippled your servers, but I'd like to know what it was.
Yup same issue bit me once too - sorting tweets by their RT count doesn't work well when the count is no longer an integer. (Fortunately I was only building a little app for myself to try to learn Ruby and Sinatra.)
Thanks, Twitter!