If it is known material, you could usually hear it, e.g. if you own both the PAL DVD and the BD. The voices on the BD sound a bit deeper then.
Here are a few examples to try.
Essentially all movies ('the hobbit' being an exception, having 48p) are shot at 24p, so that's the intended speed. Stuff made in PAL countries for TV only (TV shows, concerts, sports) can be different.
Note that PAL DVDs can also be pitch corrected (
very rare) or use other means of speedup like frame repetitons (e.g. for concerts, music videos). In the latter cases ReClock would do wrong, but for movies the PAL speeddown is essentially always correct.
ReClock can also do some other stuff:
It supports WASAPI (added natively for PDVD 14, though). And it can continuously correct the speed of the movie so to prevent dropped/repeated frames.
With DVDs it's always a compromise: Having repeated frames or wrong speed or wrong pitch or resampling or whatever. You can only choose what you find less disturbing.