Sales generally mean absolutely nothing to me.  The overall scores of the reviews also don't mean much, but the content that is in the review (what the game did good, the cool parts of the game) are often what make up my mind.

I trust reviews for info.  Nothing more.

If I'm on the fence for something, reviews will help me decide whether or not to buy it.

my opnion>everyone's else

anyway sales

Depends on the genre.

The more likely my views reflect the mainstream, the more likely i am to trust sales.

Reviews I don't trust, but i read to get an idea about the gampelay... so in a genre i don't particularly hold mainstream views, reviews are more helpful.

Depends. I had a choice of buying Yakuza 3 and Batman Arkham Asylum recently. I bought the inferiorly reviewed and inferiorly selling Yakuza 3 simply because it looks a lot more interesting to me than Batman.

Reviews!

If you are judging a game by looking at a sales number or a metacritic number than you are doing it wrong!

If you don't trust reviewers than find some you do trust!  There are so many review sites to look at that once you find people that like the same games as you then stick with them.  Also, reading the full review tells you a lot more than looking at a final rating score.  Read reviews and see the weakness and strengths then trust your own final judgment!

You can't "do it wrong". You could easily be someone whose opinion matches the aggregated opinion of reviewers exactly. It depends on what's right for you.

It really depends on the game, sometimes I trust neither and I usually disect reviews to understand weather or not I would like the game. There are a lot of biased and over inflated reviews on the internet out there. Why did Medal of Honor get a 6/10 on some websites while Black Ops got 9/10? There isn't much of a difference, except CoD has a more difficult single player.

Generally I trust reviews more, but there are a lot of fun low rated games out there, like Front Mission, Project Sylpheed, Too Human, Infinite Undiscovery, and Mod Nation Racers to name a few. However these games are generally only fun to me because they are my type of game, so I understand why reviews in general are low. This is why it's important to disect a review. 9/10 for a game like God of War is great, but to me it's a game I could beat in a rental and has no replay value, or even a deep story, so it's not for me, at least not at full price. On the same token, Front Mission gets an average score of 6/10, but IMO it deserved at least an 8/10, it's about the same quality as the first Lost Planet.

Sales are essentially meaningless to me. Lost Odyssey, Demon Souls and Mass Effect 2 are IMO the best RPG's this generation, but Fable 2 outsold them all combined. Gears of War and Uncharted 2 are some of the best shooters this gen, but CoD outsells them both combined on only one of the consoles it is released on. Halo is fun too, but I think the gold lies in Uncharted Gears.

That's my opinion

I would definitely trust reviews over sales.

For example, Super Mario Brothers Wii has HUGE sales, and I think I've played it 2 or 4 times – it’s just too frustrating and I don’t like the controller.  While Endless Ocean 2: Blue World has much smaller sales, but I like it much better and play it more. (I do realize they are different styled games - Wii Play has HUGE sales.)

Also, another thing I have noticed, is that the really good games hold their value better as used games.  Super Mario Galaxy used, was until very recently, nearly the same price as new.

Better yet is to try a demo.