Yes, it is common, but you will not hear it every day. We might also say "That is a slick looking website" or if we encounter some new piece of fancy, futuristic technology we might say "That is slick."

It is a slang word that is used enough for people to understand the meaning of it, but not really used everyday in normal conversation. In one way to use the word would be "He is slick". This would largely mean, you are to watch out for this man, he is not entirely honest in how he deals with people. Example: If you were to buy a car from him, he would never give you a proper answer of where he got the car from, or how long he had the car, or if it was ever in an accident or if it is his to sell. So, leaving you feeling very uneasy in buying the car from him.

We might say, 'that's pretty slick' when something is good.

Never use it. Yes, common. A well-known word. . Not sure that I would equate with "professional". For me it means more of the skill of the hands, or even things somewhat questionable. . He's a skilled card player - neutral He's a slick card player - possibly a suggestion of someone to watch out for & not play with? He's a slick operator in the real estate business, though he's never been formally charged with anything related .to his dealings.