Blackcatter, You tell me to F-off? You are obviously a humourless idiot. It was a joke, for christsake!
I plays whistles meself so I knows 'ow to tune 'em.
The problem is that most cheap whistles are not in tune with themselves. Like James Galway did with the flute (redesign the hole spacing and diameter), the whistle manufacturers need to recalculate the holes for each key to make each one properly "tempered". If you don't believe me, use a digital tuner to check every note on the whistles you own in all three registers - you'll throw about half of them away!