When is a non-polarized electrolytic capacitor inappropriate?
It's actually the polarity that you have to worry about more, non polarized caps can be used wherever polarized caps are used. But, there are other properties (such as max voltage, and ESR) of capacitors that need to be considered and what the application of the capacitor is.

In general if it's a power bypass capacitor, you need a higher voltage rating than the application (or existing capacitor) and a lower ESR (equivalent series resistance). 

If the capacitor is for a filter, then if you don't want to calculate how it will alter the filter frequencies, then you will need to match the specs of the cap as close as possible. 

I didn't look at the links, but as far as I know all electrolytic caps are polarized. (you can put them back to back, positive to positive, to make them unpolarized)