My Problem WIth Whites

So I've been getting some figures lately, and I've noticed that the new ones (teams made within the last 10 years or so) their whites look horrible. You can kind of see through them. But on the figures from the 80's, some have nice dark whites.

My question is, does anyone know the pattern to the whites that produced on teams? Is it random, where they painted back in the day, is Hong Kong or China good or bad?

Any tips you might have would be great. When I buy them from Miggle or Ebay, it's so hard to tell if I'm going to get a nice solid white color, without having to repaint them.