Lander On Earth

Why were the lunar landers so successful on the moon when the test runs on Earth went so badly?

The prototypes used on Earth to train the astronauts were similar in design to the landers, but weren't real Apollo landing crafts.  There were a number of reasons for this.  

The test crafts had to be able work on Earth and withstand Earth gravity.  If a real lander, designed for use on the Moon, had been used it would be far too flimsy and weak. 

As the test craft had to be stronger, it was inevitably heavier.  So the propulsion on them had to more powerful.  In fact they used jets on the test crafts, as opposed to the lander's rockets. 

When flying the test craft you also had to cope with any cross winds that you may get in the atmosphere.  Something you wouldn't get on the Moon.  They were really tricky things to fly and possibly the worse possible design for a flying craft on Earth.

So it was actually easier to fly the landers on the moon than the training crafts on Earth.