This is potentially dangerous, as it gives a false sense of security. It appears to completely ignore slang. I just plugged in "slapper" and got a green light, for instance. I notice they have a cautionary note on the site, so...?

My favourite story about this sort of thing relates to a computer game which was very popular in its home territory (the UK) but struggled when released abroad (Germany, I think?) as its name was a slang term for "rent boy". IIRC this was the game "Midwinter".