When I was using film, I normally removed all the films from their canisters so that it would be easier for the customs officer to inspect. I had no problems in most of the countries that I visited except for maybe once in Australia and, wouldn't you believe it, Singapore. Even then, there were no detectable problems on my film...even the ISO1600 ones, though to be fair, I only used one of those so can't be sure if the rest are ok.
Now I don't worry about this problem anymore. No film no problem Go digital