It wouldn't have worked. Like Assturd said: Guru could sense that Frieza was evil right from the get-go-- no amount of conniving would've tricked the Namekians into handing over the d-balls. However, even IF Frieza would have been given the d-balls/immortality, it wouldn't have changed the outcome of the Namek-saga that much. He would have still toyed with the Z fighters. He would have still jobbed long enough to allow Goku to transform into a SSJ. He would have still gotten his shit pushed in(immortality=/=infinite power/stamina/endurance.)
Hell, Frieza would have likely jobbed even more than he already did had he wielded immortality... Which would make his thrashing at the hands of Goku even funnier than it was.
Nameks DragonBalls it wouldn't work, Nameks would sense trouble and even if he got all seven dragonballs, he would need the password and the Nameks weren't about to give it up to him by any means. They'll die before ever giving it to him. As for Earth's Dragonnballs, nice or not, he would threaten the world and have immortality in his hands in no time, no longer being a slave to time.
Originally posted by Ridley_Prime
With Frieza's feared reputation, I don't think the Namekians would buy it.
It wouldn't work because the Namekians are telepaths and can sense evil in someone's heart.
When Vegeta went to take the dragon ball on Namek, the elder said he could sense the evil in his heart.