You should be okay if all the identifying markers have been changed - names, nicknames, locations. As for quotes - they are more generic that you might suppose and writers are usually encouraged to listen and use pieces of real conversations.
(I'm still trying to find a place for a great one I heard: A small group of teenagers outside a restaurant: 'I've only got one c****m left and like h*ll I'm gonna' waste it on you!) I couldn't make up one like that if I tried.
