That is not my recollection, but I don't have time to dig through BSG wikis. My recollection is that Baltar got through most if not all of the Galactica crew, and cleared everybody. Or that this was implied, in a scene like Adama telling someone else (Tigh?) about it. Something like that.
I could be wrong though.
In fact he even tells his imaginary Six (I think in the episode where Ellen came back) that everybody is going to test human.
This is a statement that he intends to lie about any positive test results that come up, as others have pointed out. It doesn't mean he magically/spontaneously stopped after Sharon. On the contrary, it's likely he kept going after Sharon - otherwise what would this statement of intent have meant?
Let's think of it this way: Adama and Roslin and everyone else believed in the Cylon test and wanted to know the outcome. Why would Baltar have "stopped"? And why would they have accepted that?
Why is there no way he didn’t test Tigh?
Well, because Tigh is a high figure and they were all very freaked about Cylon infiltrators. I guess I'd agree that it's theoretically possible he didn't test Tigh, so maybe "no way" is pushing it, but I still say it's the most reasonable inference that he would've tested Tigh.
but by the time mass testing has started Baltar has decided to fake the results.
Okay, so I guess what you're really saying is, after Sharon he went through the motions of a test on everybody, but didn't actually do the actual test on anybody. Well, that's possible, but why not? Wouldn't he have been, at least, curious to know himself? even if he didn't intend to out anybody.
I really don't know though, I admit. I guess I find it implausible that he developed this test, everyone believed in it, but that he somehow didn't test the second in command. And I still believe the show gave the impression that Baltar cleared everybody - with his test. This would have meant that he would know Tigh's Cylon status (even if he didn't tell anyone else). You, however, have come up with a scenario in which he not only decided to fake everyone's results but decided not to even do the test on anybody.
I acknowledge, under that scenario, there would be no inconsistency vis-a-vis Tigh being a Cylon and vis-a-vis Baltar not knowing that he was one. This is all a very murky and convoluted justification though for things that should be straightforward and transparent IMHO.
We have no knowledge of anyone else that got tested. There’s really only two episodes where anything happens with the testing, the ep where Sharon gets tested and the ep where Roslin keeps trying to get Adama tested and he keeps trying to get Ellen tested. Outside of those episodes there is absolutely nothing that indicates what’s going on with the testing. And even if Adama said something like that who says Adama has been told the truth, again Baltar has decided that no one is testing negative, once you make a decision like that there’s no reason to actually DO the tests. It’s a lot easier to not spend 11 hours testing somebody and say they’re human than to spend 11 hours testing and ignore the results.
Nothing magical and spontaneous about it. Why do the tests if you’re going to lie about the results? It’s not like these are quick 5 minute tests, 11 hours each, no parallel testing possible, 61 YEARS to test the entire fleet. Why bother? And remember the statement wasn’t that he was going to lie about the tests, the statement was that everybody was going to be human, big difference.
Think about it this way, Baltar got reminded by his head six that positive tests could be dangerous, why risk it? Sure Roslin and Adama want to know, but he’s already decided he’s not telling them about any Cylons, why run the tests if you’re going to fake all the results. Think like a horndog amoral scumbag like Baltar: are you going to spend 61 years of your life doing these tests, which will seriously impede your sex life, just to ignore the results; or are you going to spend 5 minutes every month spacing 60 blood samples and make up the same results you were going to say anyway?
TV writers give you clues to stuff. When numbers start getting thrown around there’s hints about how things are going to work. When the numbers came out that each test was 11 hours and it would take 61 years to test the whole fleet that was TV writerese for “the test is a McGuffin that’s run it’s course, no Cylons will be detected by it, time to move on”. For most of the show people have died faster than they could have been tested, heck if you’re not going to fake the results when you’ve got that kind of math there’s really no reason to do the test.
But again, why test ANYBODY? There’s absolutely no reason for Baltar, remember who we’re talking about here, to test anybody after his scientific curiosity was satisfied. Once he knew the test worked, and once he decided everybody was going to be human, it over, he washes his hands and moves on. Remember he’s never in the lab again after the Ellen episode, that’s a clue. You see characters where they spend time, at 11 hours a test if Baltar was actually doing the work he’d be in the lab a lot, but he wasn’t.
The why not is time. 11 hours a test, 61 years of work, given birth and death rates a Sisyphusian task, given normal non-war time death rates half the people would be dead before he finished the task, given the death rate in the rag tag fleet forget it. Just think about how many Galatica personal were killed when the Cylons boarded, if he’d taken the 11 hours to do the test (with his own predetermined results) that’s a lot of time wasted. He’s got nothing to gain knowing who all the Cylons are, once he’s lied about the results to Adama and Roslin he has no blackmail leverage, what’s he going to do threaten to “admit” he screwed up a test and months later decided to redo it? Also remember his part in the genocide, it’s not like knowing who the Cylons are tells him who wants him dead, everybody wants him dead they just didn’t know it yet.
I don’t think the show gave the impression that he tested anybody after Ellen, and truthfully the show doesn’t give much of an impression that he even bothered to genuinely test Ellen. I thought after the Ellen episode that Baltar was done actually doing the tests. There’s simply no way to believe Baltar, self serving egotistical horndog Baltar, would perform the most boring inglorious 61 year task in human history, especially once he made it clear the results were pre-determined. Doesn’t seem murky or convoluted to me, seemed obvious in Season 1, with Ellen the Cylon Test plot line was done, and other than asking why Sharon tested human that was basically the last we heard of it.