We know that Master Yoda remained on Dagobah to make use of the Living Force (and more importantly, the powerful Dark side energies) of the planet to help conceal himself during his self-imposed exile. According to StarWars.com, Dagobah was:
a swamp-covered planet strong with the Force -- a forgotten world where the wizened Jedi Master could escape the notice of Imperial forces.
However, in all of the descriptions of Tatooine, I've never read anything that would seem to indicate that the desert planet afforded any such Force-masking qualities to its inhabitants. If the Empire was, in fact, actively seeking Jedi for extermination, such powerful Force presences should have stood out on that planet like a beacon. At the end of Episode III, Yoda tells Obi-Wan that he has further training for the young master.
Master Kenobi, wait a moment. In your solitude on Tatooine, training I have for you.
Which means that Obi-Wan would be actively tapping into the Force while on Tatooine, which, again, would suggest that he's basically sending up a flare to anyone looking.
Finally, Luke was able to sense Darth Vader's presence in the Sith Lord's Star Destroyer above the forest moon of Endor before they arrived. It would seem to me that Vader may have been powerful enough to sense another Force user on the planet's surface while they were in orbit above Tatooine when capturing Princess Leia's "diplomatic" ship.
So, did Obi-Wan do or have some artifact or ability that actively dampened his (and Luke's) Force "radiance" from being noticed, or did the Empire simply ignore Tatooine as a possible haven for Jedi due to the Hutt control of the planet?
