Materials looking weird on certain meshes

hi all,

I have a very stupid questions concerning a topic that causes my headache since a couple of days.

Whenever i put a material on a certain cube mesh or a mesh with low vertexes it looks ok. But when I’m importing certain sphere-shaped meshes or meshes like on the picture below the materials are looking awful.

I’ve tried to play around with UV-Mapping in Blender and change the Texture coordinates of my materials in UE4 but somehow all materials are looking kinda blurred on that mesh you see below.

can anybody tell me the exact problem in this case? Do i have to set the texture coordinates extremely high/ low? or is it a UV mapping problem? i have no clue…