> If I speak bad French with a French person... may God have mercy upon my soul. Especially if I forgot to say bonjout/bonsoir first (abomination! burn the heretic!)

These are two very different things. In my years of experience, the most likely outcome of speaking imperfect French is just that the French person switches to speaking perfect English.

Not saying hello+good morning is a social sanitation faux pas viewed akin to not washing your hands after using the toilet.

I'm not going to defend the latter, because it's all very formulaic, but I lived in France for years without proficiency and never had a poor encounter because of my unskilled French.