Justin Bieber is a Canadian singer-song writer and musician who rose to fame when 'Scooter' Braun discovered his 'talent' on YouTube.
Upon signing to Scooter's record labels - RBMG Records (partly founded by Usher) and School Boy Records Bieber went ahead to release the song that would launch him into super-stardom to become an idol for mainly vulnerable teen girls with low self esteem; more commonly known as 'Beliebers'.
In 2013 an internet Troll started the trend on Twitter #Cutforbieber and this truly exposed just how vulnerable and crazed some of Biebers fan group are with many 'Beliebers' responding with photo's of them slashing their wrists for their idol.
So to respond to your question -
No, I would not smell nor lick Justin Biebers feet especially after a concert. I'd advise if Justin Bieber asks you to do this that you swiftly decline and report the incident to the police assuming that you are under the age of 16 (which is highly likely).
However if you are of legal age and tempted to smell and lick Justin Biebers feet please check out his Deposition Video:
Also see this list of his career low-lights and his relentless disregard for anyone other than himself -
http://www.theglobeandmail.com/life/celebrity-news/justin-biebers-bad-behaviour-a-recent-history-of-all-his-lowlights/article16462970/