Please define "dirty old man"

Yes, but not harassing others like many do here. There’s a huge difference.

Often they push this on unwilling others. That's the line. Don't be that guy.

Dirty old men are those who openly flirt with people who are paid to be nice to them, like nurses, waitresses, airline stewardesses and cashiers. Those who feel women's bodies are free to be pinched and groped. Those who never miss an opportunity for an unwanted sexual joke or inuendo.

Showing the youngsters how its done...

Don't be jumping in muddy puddles and take your shoes off before you walk on the clean carpets.

If they grossly perv on everyone in sight especially super young girls its cringy eh?

old is synonymous with decay, natural law say they are wrong and anti nature.

The term "dirty old man" refers to an adult male who is sexually interested in girls. There is no age criteria that defines a man as being a dirty 'old' versus a dirty 'young' man. The term originated in Great Britain and spoke to the ultra-conservative Victorian bias that Brits once put on anything sexual.