One who makes a show of liking another person with profuse or excessive displays of camaraderie, such as vigorous hand clasping, back-slapping, hearty words of greeting, etc.
handshaker
noun
One who gives a handshake.
A deceitful person, a swindler.
How often have the words backslapper and handshaker occurred in a corpus of books? (source: Google Ngram Viewer )