He seems like a decent chap, and overall I think he is probably cared the most about the Baudelaire's well being, but his complete inaction over the Stephano incident is pretty poor form. Not only does he fail to recognize Olaf, but he ignores the Baudelaire's protestations. And also, he missed the sebald code in Zombies in the Snow! But other than that, yeah, monty is pretty alright.
When I read the series as a kid, I thought Uncle Monty was the best guardian out of all the guardians the children had, and I thought that made him a good guardian. But now I would argue none of the Baudelaire's guardians were good guardians because even though some of them were nice people, none of the guardians protected to children from Count Olaf. Uncle Monty knew a lot about snakes, but who would be such a blithering idiot to not notice when someone is walking around their house with a knife 24/7? And the children flat out told him "Stefano" was Count Olaf, and he kept going on about spies from the herpetological society. He may have been the best guardian the children had (although I would probably go for Hector on that matter), but that did not make him a good guardian.
That being said, I do love cake.
Faith is being sure about what we hope for, being convinced about things we do not see. Hebrews 11:1
And the children flat out told him "Stefano" was Count Olaf, and he kept going on about spies from the herpetological society.
Yes, especially considering that Stefano arrived only after Monty adopted the Baudelaire kids.
It occurs to me that if there isn't one already, there really ought to be a fanfiction/parody where Count Olaf stayed in hiding after TBB; Stefano really is a small-time spy from the H.S., Captain Sham is a genuine old sailor, etc.; but the Baudelaires, traumatized by their experience with Olaf, hallucinate all these innocent people to be him in disguise.