Irregular spots on my textures

 Hey community, 

• Recently i was applying textures to my model in blender.. The texturing process were fully made in substance painter..

The issue I am facing is that...I am getting some grunges or blackspots on the textures when it is being applied. 

I have never used any height maps during my texturing process 

It's just that when i am applying textures in blender these weird spots stick to my textures..

Is there any reason and solution to this ..??

Pls let me know