Amen! Make it clear!

If you want to change the values in a hash, use hash notation consistently throughout ... precisely so that Perl in its DWIM-crazed way does not decide that you “meant” something that you didn't even know you were doing.

And then, once you know you have a hash, and that no goofy hash-to-list-to-hash magic is happening behind your back, always assume that the keys will be retrieved “in no particular order.” A hash is intended to be used as a high-speed, but random-access data structure.