He was an unlikely politician, with his hunched shoulders, bad comb-over, boxy suits, lateral lisp and rictus smile. He had no charm or charisma, nor even really a discernible ideology. Giuliani’s mother said in an interview published by the investigative reporter Wayne Barrett that he switched his registration, after Ronald Reagan’s election, from Independent to Republican — he was a Democrat before that — in order to advance his career. (‘‘He still feels very sorry for the poor,’’ she insisted.)