Thats not 100% true but yes if you use crazy bump on a defuse and than don't got right settings it will be look like shit normals like mine in the past crazy bump is a powerful tool and thats true but i would recommend to use hight maps with gray white and black to reveal the hights the specualair and bump map from crazy bump are atm not good settings i would play around with the settings if you stay at defuse bump mapping also a handy tip i made for my self to use crazy bump is for the specular to do this

My settings : for bump map

intensity: 25 - 30

Fine detail: 50 - 60

medium detail: 50 - 60

Large detail: 50 - 60

very large detail : 50 - 60

for bump map than save as what you want its need to be looking something like this

also don't forget to save the specular and than do this

you take the defuse make go to image -> adjustments -> desaturate than hard light it on the specular from crazy bump than make new layer fill it with black and also high light with 50 - 70 opacity and than merge that and use on the alpha layer from the normal map

the specular needs to be something like this.

than the reference map aka specular map will be lowering the crazy bump defuse normal map

But the best way i learned not so long time ago is to make a hightmap and than use nvidea normal map plugin something like this

so thats a bit of my trick to make a good crazy bump normal map i don't say its good but its handy and fast.

Boba Fett 2D/3D Artist