Conversation so far:
What was Bruce arrested for?
On October 4, 1961, Bruce was arrested for obscenity at the Jazz Workshop in San Francisco.
Did he get jail time?
Although the jury acquitted him, other law enforcement agencies began monitoring his appearances, resulting in frequent arrests under charges of obscenity.
What other times was he arrested?
Bruce was arrested again in 1961, in Philadelphia, for drug possession.
Any other arrests?
again in Los Angeles, two years later.
The Los Angeles arrest took place in then-unincorporated West Hollywood, and the arresting officer was a young deputy.
Did this arrest record have any negative effects for Bruce?
Solomon later saw his conviction overturned; Bruce, who died before the decision, never had his conviction stricken.
Who was Solomon?
Bruce and club owner Howard Solomon were both found guilty of obscenity on November 4, 1964.
What is considered to be "obscenity" in these arrests?
he had used the word cocksucker and riffed that "to is a preposition, come is a verb".
Any other words that were considered to be "obscene"?
The specification this time was that the comedian had used the word schmuck, an insulting Yiddish term that is an obscene term for penis.
Were words the only reason he was arrested for "obscenity"?
he played at Peter Cook's The Establishment club in London, and in April the next year he was barred from entering England by the Home Office as an "undesirable alien".

Question: Why was he considered to be an "undesirable alien"?
Self-contained rewrite: Why was Lenny Bruce considered to be an "undesirable alien"?