Having an opinion that is not the mainstream opinion does not make me a contrarian. For the past few years I would say that my opinions have been the same and have not changed to be the opposite of what is popular. I am not a clown or joker either. I do not make jokes on this website.
It depends on the reason why someone has the opinion. A contrarian takes an opinion because it is the opposite of the mainstream. It is describing the reasoning of taking an opinion and not about the opinion itself being contrary to the mainstream.
For example. Person A is selling a car that is severely cosmetically damaged. To get a better deal they hide the appearance of the car for privacy reasons. When the buyer finally gets the car they realize that they overpayed because they didn't know how bad it was.
This to me would be a case of fraud. Whether commiting fraud like this is illegal is a legal question.
If you want another example with the buyer withholding information then imagine a place where kids 5 or under get a discount. Someone brings their child who is 6, but is small for their age. An employee applies the discount thinking the child is 5 and the parent says nothing. Revealing someone's age is a privacy issue they may think to themselves.