The basic answer to your concerns is no, HIV cannot be transmitted by a contaminated razor. HIV is an extremely weak virus and dies once exposed to the air. It cannot live outside the body. Sharing razors is generally not considered good hygiene for the same reasons as sharing a tooth brush or eating utensils. There is a possibility for Hepatitis (A/B/C) as this virus is much stronger than HIV and can live 3-4 days on a surface outside the body. I am 100% sure HIV cannot be passed in this manner because it is impossible and there has never been a confirmed report of transmission in this manner anywhere in the world.