PAL60 and NTSC50 are uncommon standards which only get displayed properly if you own a multi-system TV or an Amiga RGB monitor, or of course some other expensive device capable of it.
When you run a PAL game through WHDLoad on your NTSC Amiga with a PAL tooltype set, this is exactly what happens with the display. It becomes NTSC50. You force 50hz through NTSC. Try and watch this on a standard NTSC TV and you'll get a black and white picture. Composite or S-vhs do not cope with PAL60/NTSC50 well, unlike RGB which is totally unaffected.
The same goes for when playing an NTSC game on a PAL Amiga through WHDLoad with NTSC tooltype. You force 60hz on PAL.
This was a HUUUGE problem when CD32 came out in N. America. Commodore expected the average joe console gamers to cope with PAL/NTSC issues and TV sets. Many games were released in PAL version only, yet they were sold on the store shelves in N. America and when ran on NTSC CD32 units, the usual issues started to occur. Later on, the users learned that in order to display PAL properly they needed an Amiga mouse in order to hold two mouse buttons and select PAL from the early-boot-menu, however, only to end up with black and white display, since they now forced NTSC50 in effect. What was the next move? Buy an expensive multi-system TV and end the problem....right. Stupid Commodore.
Just do a google usenet search and see how many people were confused about this. NTSC CD32 was doomed right from the start. Is there a TRUE NTSC CD32 game out there?