When I select glasses for any model it gives me some ugly glasses, so how would I get police glasses?

I suggest using F5544's Improved State Trooper modification as that will add in two new pairs of glasses in game. One pair you can easily equip using Simple Native Trainer and the other pair, as far as I know, you can only equip by going to the Russian Clothing Store right near Niko's apartment. There you just have to buy the glasses. I suggest using the pair you buy from the store as those are just all black sun glasses. The other pair is just some regular more modern looking glasses. Hope this helps  .