I downloaded some psd to show my mockups, but it looks like the text is going to be blurred when I put anything inside the distorted smart objects. How to avoid this problem?
The "blur" you see is due to photoshop trying to calculate the way your type should look at the particular perspective and adding anti-aliasing . Simply put I don't think you can fix it. I would recommend using a different mockup psd that is not as skewed as this one. Here's a site that has a few samples you can choose from. If you take a look at all mockups at this angle you are using will notice the same blurring. If you are dead set on using this, you may try adjusting the actual aliasing of the type in the smart object.