Goq – it may not be a catastrophe but it is basic grammar that is learnt in primary school and shows major ignorance from the people who misuse apostrophes in plurals. I get worried when I see basic spelling and grammar mistakes written on letters that come from schools (as an example) – a person who cannot use English properly, teaching? The best education we can give to our kids is to employ educators who are themselves educated.
(On a side note connected to this last point, I have seen teachers who are excellent at teaching and discipline, but actually have no idea what they are teaching about and are making major mistakes in their material).