The only strings I've had problems with so far are the ones that come with BKPs, the Rotosounds.
Out of the box at least three sets had a kinked string, which I threw out. Thankfully they were different strings, so I took them from another set of Rotosounds from a different BKP box.
I also snapped one at the bridge, but I've also done that with a Dunlop.
Here in Adelaide rust is not so much of a problem. The worst rust I've seen on a string (besides guitars that have just been let go to shite) was on the SG Junior I bought via ebay from a guy in Queensland. Much more humid up there and in the photos it looked like he had been hanging it on a wall rather than keeping it in the case. There were dark brown rust patches around the pickup area of the low strings. No idea what brand they were but I'm guessing it was caused by either sweat or humidity.
A crust punk friend of mine lived in Darwin and during the wet season everything went rusty, including the studs on his denim jacket