But, look at what he had to go on...
Saul had just visited the car-wash and told him that Huell was missing. He then gets the pic of the money in the barrell, followed immediately by the phonecall from Jesse which details how he tracked the location of the money using Huell which led to the rental company that used GPS in their vehicles.
Now, given time to analyse that Walt would probably have realised that a rental company wouldn't just offer up GPS data without law enforcement involvement, but he doesn't have time to analyse exactly what is happening. The deception was so good and revolved around the 1 thing that would instantly cause Walt to react like that, that it was far from disappointing for me. In fact, conversely had he somehow sensed he was leading them to the actual location ahead of his realisation in the desert I would have been disappointed that they had somehow made him totally infallible. Yes he is a very smart guy, who thinking rationally would have seen it coming - but at the point in the characters development he is led as much by emotion as rationale! And this is what Hank and Jesse (and Gomez) were counting on.
This. I was shouting at the TV hoping he'd hear me
