I hate it when random people come up to me and ask me to cover my face.
It doesn't matter whether or not they were 'polite'.
It offends me.
I might be someone who believes that covering one's face is a Bid3a. They should all consider that before asking anyone to potentially do something they don't believe in.
How would all those people feel if I went around asking them/their wives to take their veils off because I personally think it's haram? (I'm not saying I do.)
However, I have noticed that veiled women commit Bid3as as a result of wearing a veil. They pray with it on, for example.
And more importantly; It's no one's business but mine what I dress like. I will not take these people's advice, nor will I ever appreciate it.