Joseph Moore (57) also told the officer he would “get him off duty” and kill him when he violently struggled as he was arrested.
Moore, of Highfield Estate, Newbridge, Co Kildare, denied obstructing a search and threatening, abusive and insulting behaviour.
Finding him guilty, Judge Paula Murphy said Moore’s account was not plausible and gave him a one-month suspended sentence.
Dublin District Court heard a garda saw the accused in a suspected drug transaction in which he took an object from his mouth and handed it to a man at Wood Quay on September 21 last year.
The garda told Moore to open his mouth and saw what he believed to be two deals of crack cocaine.
When told to spit them out, Moore swallowed them and pushed the garda away before saying “f**k you” and refusing to reveal his identity.
He was arrested after a violent struggle in which he heavily resisted.
Moore gritted his teeth and shouted threats “right in my face”, the garda said.
“I will get you off duty, I will kill you when these handcuffs come off, you’re a scumbag,” the accused had said, in view of members of the public.
Moore maintained he had been leaving an appointment in Dublin City Council’s offices when the garda approached him, jumping off a bike and saying: “Hey you, come here.” He said the garda asked what was in his mouth and he replied: “I have nothing but my dentures.”
He denied using bad language and said the garda put handcuffs on him straight away. The garda said a common “MO” for drug dealers was to “deal from the mouth”.
“Dentures don’t resemble crack cocaine,” the garda said.
Moore had been on methadone for 20 years, his lawyer told the court.