Do manufacturers lie about the specifications of their components?
In the general sense, I have never known a reputable electronics device manufacturer to deliberately lie about the performance of their products, although the datasheet may be updated to reflect more complete test results.

A preliminary datasheet should be viewed with a bit of caution as the device is unlikely to be fully characterised at that point with some graphs and entries calculated rather than measured.

A bigger issue is understanding component specifications (typical subjects linked). 

The time when someone has deliberately lied is where a counterfeit component is sold to you. As noted in the comments, many (but by no means all) of these are sourced from China.

This is a major problem in the high reliability arena and although convictions do occur, the problem persists.

The reasons are numerous; the issue in avionics (for instance) is that boxes may be 40 years old and sourcing components for repair is incredibly difficult (and expensive); the financial gain for a successful counterfeiter are large.

Other industries face the same problems.