i have no idea why this game keeps selling i wish that game would just die already

It depends on why the game is reviewed as 'bad'. If some review called the game bad for "lack of storyline" or "too easy", then clearly they don't know how to review a casual game.

Having played some of the mini-games myself, I can honestly say that the BIGGEST reason why I would call Carnival game a "bad game" is the fact that some control scheme just failed to perform up to standard. Some of them are just downright BAD.

I don't care if it's a casual game, if it won't do what I want it to do (what it SHOULD do), it's a bad game regardless. 

A few notes on Carnival Games

It is still selling for $40 (USD). For a system with a lot of $20 shovelware, this is not a "cheap" game.

It is bundled in some places though -- Office Depot for example -- which can lift sales.

It is also one of the few third-party titles with healthy advertising. People see it appears to be fun to play and ask for it buy name. It was also in short supply for a while after its debut, making it a "must have" item.

Some of the games are "spot on" while others are "not so hot" in their control mechanisms. Though I will say that with a little work, almost all the games are playable.

Plus, if you go to a carnival and want to spend money at the midway because the games seem so easy ... having this title will save you some coin.

I have a lot of Wii games -- including many a mini-game collection. This is no where near the worst game out there.

So those of you who would love to dismiss Carnival Games so you can play GTA IV -- remember without this title, 2K's financial picture may have forced it to do things very differently.

Mike from Morgantown

Its getting awful close to Bioshocks LTD lol. Take 2 must be like WTF!?

But honestly? Its because the casual gamers that 360 and PS3 fans spent all last year claiming wouldnt ever buy any games, and would just get tired of Wiisports then put the console in the closet started to BUY GAMES. Its funny, because those people swore the casuals wouldnt stay interested, now Carnival Games and Mario Party 8, Mario&Sonic as well as stuff like Lego Star wars (also just passed a million sold) are burning up the sales charts and they are now in THIS THREAD crying foul about how they wish these games would stop selling.

LOL IMO.

Because we are stuffy elitists who spend our time on emssageboards looking down on these people and insulting them whil they enjoy the games they like to play.

Because it's the cinnamon sugar swirls in every bite?

Obviously there are people who either find it fun to play or who have children that may enjoy it. It doesn't look like something that I would care to play much and probably the same for you, but we are far from the majority.
That's about all I can think of as reasons right now.

Because is fun.

I think you are missing a very important point. The same people who have sworn the casuals wouldn't stay interested, STILL won't buy those games. there are just more casual gamer buying Wii and trying out the game.

 In fact, Carnvial game is an oddity, considering other games (third party games) still don't sell well.

It's fun and absolutely genius in it's simplicity. You get 25 mini-games, but because they are all from a carnival, and on Wii, anyone and everyone immediately 'gets it', they know the included games immediately, can see the fun in it, and feels confident they know what it plays like and it seems like good value since there's so many mini-games (compared to Game Party, Playground, etc.)