What's wrong with the bold?

Quality is measured by review scores ?! I think you need a reality check on that one. 

Game sales do show appeal but at the same time you've yet to tell me why game sales don't mean quality. 

Then tell me how I am wrong ? 

Quality IS measured by reviews. Not review scores but reviews regardless of them being professional or not.

Isn't that the point of a review score ? To infer whether the game is bad or not from a review ? Is it measured by the amount of reviews ? Again your not being very specific here. 

How do you come to buy a game? You either seen a commercial, poster, or heard a friend talking about it and from those little pieces of info, you subconsciously determine if it sounds interesting to you or boring/bad. If you are on a site like ebay or at a store like Gamestop purchasing a game at the counter, it is 100% safe to say that the game appealed to you in some way shape or form.

The word of mouth from friends usually work best otherwise they won't mention it. Advertising means nothing for the most part if your game is trash. As for the rest what was the point in saying the obvious ?

You CANNOT know the quality of it just by looking at it and buying it. You will need to have PLAYED the game in order to determine if it was quality or not. After that, whatever you think of that game is pretty much your review of it.

It's true that you need to have played the game in order to know that it had quality but at the same if it had bad quality then it won't sell well in the long run because sales will drop very quickly mainly due to having no worthwhile mention. Whatever you think of the game is not what everbody else will think of it. To say that the top selling WII games were shovelware is ignorance on your part because at the same time they were system sellers. Why would the masses go purchase a system for bad games ? Consumers are more concious about spending than you think they are and they never lie about what they want.

If you went to a friends house and asked "Hey, you played the new Super Mario 3D world game, right? Well is it any good?" and your friend says " yea man, its a great game. Its the best Mario ive played in a few years" then your friend just pretty much gave you his review of the game summed up in 2 sentences.

How do you know if your friend is not biased ? There's a clear difference between the masses and the forum dwellers here like yourself. Your example does not show the reality. Most of the people that played SM3DW are not mentioning it as "good" but instead are keeping silent about it ? Why is that ? 

Sales DO NOT = Quality

That right there folks is what you'd call a bad conclusion from awful examples. 

Are you implying that a quality game is only a quality game if it sells a lot?

What's the problem with that ? 

So the game that sells less than, lets say 3 million is a bad game?

Then tell me how I am wrong ? 

While quality is subjective and differs from person to person sales do not equal quality. It's simple really since games are interactive entertainment you would have to you know interact with it to be able to judge this quality, only after doing this would you be able to judge the quality of that game (since people have different taste a quality product would differ depending on the person).

Now unless you are  telling me you have the ability to judge the quality of a game without actually playing it I just explained to you why you are wrong.