I partially agree with you. It is true that confidence scaling does not inherently mean anything, but there are cases where it does, like if a character says that character A can beat character B, yet they believe they could beat character A then they should be scaled to the power of character B (as long as they know how strong B is).
For example, Gouketsu scaling to Darkshine because, even if he saw his full power and knew Saitama is stronger thought the entire S Class was needed to defeat him is iffy, but understable in a certain way. Genos has shown the ability to analyze strength, as shown in the VGS Audiobook where he could collect data from everyone he fought and it to be considerably reliable. You could, maybe, apply this also to how he saw Tatsumaki reflecting the bombardement. Though for Gouketsu it is entirely unnecessary, you could take off all his scaling and He'd be still the tier he is given he scales to his own feat.
Psykorochi scaling to Orochi also falls under this. If Orochi failed to defeat Saitama with his strongest move yet thinks Psykorochi can do the work, that certainly shows Psykorochi is indeed more powerful than his Gaia Cannon.
HE and Black Sperm scaling to Gyoro Gyoro because Psykos herself thought they could beat Tatsumaki, who defeated her is also a reasonable.
One I find invalid, though, is Boros scaling to Gouketsu: the Saitama who said Boros was 'strong' is weak compared to the one who fought Gouketsu, to the point the Saitama who fought Gouketsu could one punch Boros' fight Saitama and did not found him anything remarkable. So, of course Gouketsu, who is far below said Saitama, wouldn't be called strong regardless how strong he is. And, well, for that very same reason I disagree to scale Boros to any other monster that happened before him just because Saitama didn't say they were strong.