We all make decisions by evaluating trade offs. When you buy a car, a bigger engine (more CC) will run the car faster but will also consume more fuel. We all want a bigger faster car which consumes less fuel. So if any car maker can claim that, you will buy that. To do that, Car makers will have to tweak the performance for the demos but have to revert back to normal as in real life to deliver the promised fuel consumption.
For the Handsets, it is even easier. You will look to benchmark reports directly if you are a geek or build favorable perception by reading positive reviews as tech media uses the benchmark reports to decide if the handset is fast or not. In reality, the handset is not as fast as it should be but it delivered the battery life as promosied.
Samsung is guilty of deception but we consumers also to be blamed. Why we blindly rely on others to tell which handset is better? Just go to a shop and try the handsets for 30 seconds. That should give you very good idea. Tech media should rely on actual usage and only then recommend a product. Just passing judgment based on Benchmark reports is not journalism, it is like re-printing of press release.