As far as I know I have not been "clocked" for well over 25 years... then again as I havent ever asked anyone I might just be unaware. Also I dont do the parnoid stealth thing - so I do tend to tell people, perhaps not immediately, but in the course of conversations or whatever. So its impossible to know. All I can say is I've never been made to feel uncomfortable, threatened, discriminated against, disapproved of, or like an outsider or anything different, so functionally I don't think it matters. Its a massive non issue - literally zero.