[JoshTriplett]

It absolutely is. Some journals have more peer review than others, and experts in the field typically know which ones will effectively rubber stamp anything that crosses their desks. That doesn't inherently make the research wrong, but it means the usual "this was published in a peer-reviewed journal" signaling carries no weight.

[robot22]

Peer review is less effective then you imagine and a highly political process. These experts usually have a vested interest in a certain viewpoint or line of research. I agree extra scrutiny always helps, but scientific consensus does not guarantee truth.

[joe_the_user]

Well,

We should also look at the article under consideration. It seems to describe a molecule that might "cure" or ameliorate the effects of aging. Extraordinary claims need extraordinary evidence but even more, there's a big "push" to have something like this published given that in there would be a tremendous amount of money interested in investing in a project that appears to have even a one percent chance of being that big.

[JoshTriplett]

It's certainly not a guarantee. However, it does tend to provide a non-zero improvement in signal-to-noise.

That process can and should be drastically improved, though.