That's a pretty amateurish thing to say I think Stopend. Every animal is different. Some are dumb and will let the dog work away and some know what's coming and won't sit still for any dog until a couple of hours run about.
'You only get out what you put in' is so true. Highly strung, annoying terriers aren't for me and are easily sorted if raised properly.
Like has been said, the best ones I've seen are real laid back types.