My sister and my mother went to a shop to buy few things. The shopkeeper asked my sister her relation with my mother. She said, "She is my mother". Despite the fact that my mother had covered her head and face, he replied," She looks so young, and I thought she is your sister." Let us not discuss here my mother's response, the shopkeeper sure won't commit this mistake in future, inshaAllah.
And I do realize why he said it, because a lot of women do like to be called young when above 40, and such compliments do work for those shopkeepers in few cases to be able to make good customers.
In general, it is amazing that a Muslim woman at times don't mind compliments of her beauty online or in practical life coming from a MALE STRANGER !? Isn't she suppose to give this right to only her Husband ? Same goes for Muslim men. Compliments of their good looks coming from a na-mehram woman seems very odd.
First thing we are not living in 14th century, secondly Muslim women don't mind compliments for her beauty online, coz they feel secure their. They love it offline too, if no body is around.
Secondly complimenting opposite sex is not wrong at all in any way, as a guy i can assure you we are not full with lust all the times !