“marital ( between man and wife and not on film) sex is not dirty and anyone who thinks it is ...is strange.”
Just because it is done in love does not mean it no longer involves physical contact between various areas of the body that are highly susceptible to passing communicable diseases back and forth. If married couples bring STDs into the relationship, they’ll pass them back and forth. Even if they start out clean, there will be a likelihood of infections, rashes, and so on.
To say that married sex isn’t dirty is like saying married homes can’t carry infectious diseases. I suppose married houses might be better kept than single ones, or married sex is relatively more safe than single sex. But some activities are dirty in themselves.
I don’t know if you are married, but if you hop up and disinfect yourself with Lysol after every romantic encounter with your spouse, you must be hard to live with.