It seems that different words fell out of favour at different times. One person is unlikely to have decided that a word is suddenly rude. Social change and attitudes progress and words become unacceptable.
For instance some words that were used 40 years ago by white people to describe black people are no longer acceptable, but many years ago not many would have batted an eyelid at some of the now taboo phrases. This is a result of a change in social attitudes.
Many of the more influetial Victorians generally led church going lives and lived by a high standard of etiquette.
Anything outside of that strata of etiquette would have been considered unacceptable and so social change would have deemed previously acceptable terms, no longer acceptable.
There is an interesting article about swear words here.
http://www.bbc.co.uk/dna/h2g2/A753527