rubber trim around windows and dressings

I'm sure this has been brought up before but I don't search and through my phone it doesn't let me anyway. The rubber seals around like the windows seem to be a harder type of rubber (not really flexible) and I can't ever find a product to dress them. It either doesn't do anything, looks worse after dressing, or if you can visibly apply it, it looks smeared and ugly. I've tried several products that I have used on exterior plastic, tires, door seals etc with great results but it is just something about around the windows