[Isidar]

I know this is a common woocommerce error but I can't fix it. My product images were blurry but I fixed that somehow, but the catalogue images/thumbnails are still blurry and it looks terrible. 

Anyone know of a fix?

[Rectal]

Images are most likely to small. Image size depends on your theme. you can check by going to "WooCommerce > Settings > Products > Display"

Lets say your theme calls for 800x800 and you are providing images that are 400x400. It will stretch the image and cause it to be blurry.

Other issue is the image quality/resolution is just bad.

Let me know if you need further assistance.

[Invincible]

Like Rectal said most likely a resolution problem, another thing you could do is check the resolution of your images in the media section and compare it with the default thumbnail size specified in your theme settings.