goku couldn't sense his life,not his ki.everyone there was ki sensor,but nobody noticed that,only goku,gohan even had no idea what his father was talking about. why? because he is a genki-dama user. genki=stamina=life,so don't they have stamina? no,they have better stamina,a different one.Chapter: 441 (DBZ 247), P4.4
Context: as Videl fights Spopovitch
Goku: “Like I thought, that Spopovitch guy is weird…He seems too fine, despite the fact that he should have taken so much damage, and I can’t sense any life from him…”
normal life form's stamina = genki
majin race's stamina = magic or demon ki (i will call it majin ki)
the majin ki cannot be sensed.
since they can't sense some of majin boo's ki,the power they sense is never accurate. after absorbing the kaioshins,boo might have some genki (since the original buu has better stamina),it works like this:Chapter: 476 (DBZ 282), P10.5-8, P11.1-3
Piccolo: “Goku…There’s something I want to ask you while I’ve got the chance…[ ] …That Super Saiyan 3 thing earlier…if you had gone all-out, wouldn’t you have been able to defeat Majin Boo?...How about it, am I wrong?”
Goku: “Nah, I don’t know…When it comes to Majin Boo’s strength, it’s like a lie…I think that I probably couldn’t have won…”
before: 50% majin ki + 50% rest of the ki
after: 30% majin ki + 20% genki + 50% rest of the ki
the proportion of sensed and not sensed ki changed after absorbtions, that's why goku and vegeta were terribly wrong about kid buu.
fat boo's sensed ki(70%): 70
real power: 100
ssj3 goku: 150
goku's conclusion: i could beat him if i wanted
kid buu's sensed ki(50%): 70
expected power: 100
real power: 140 + superior stamina
goku's conclusion: I thought things would go a little better than this.
