Some of the puzzles in Escape from Monkey Island are very well clued. For example, figuring out how to get into the bank on Lucre is tightly integrated, though wacky. You pick up a manhole cover, and notice that there is writing on it. It gives the names of people involved in a love triangle. Then you discover that the man running the prosthetic shop will give you random prosthetic organs if you fill in the blanks of his mad-lib stories. And, aha, he asks you for the names of people. What about the names of the people from the manhole cover? In that case, he gives you some skin -- which you should then use on the open manhole. It's all tied together, in a strange sort of way.
Some of the puzzles lack that sense of linkage. For instance, to get Ozzie Mandrill to break his cane, you have to spray the nasty pirate scent you've created on an object near his chair. That's hinted at: ask Ozzie what he hates about pirates, and one of the things he will rant about is how pirates smell. But why do you want to displease Ozzie like that? Mainly because you can.
Then there are the completely unmotivated puzzles, the ones with so few clues as to be well-nigh unsolveable on your own. F'r instance, creating the pirate scent. What items should you put in the empty perfume bottle? All the ones you can. Why? Who knows. You have to try using the bottle with most anything you come across until you have completed the spray.
This is not good. I don't mind somewhat-illogical puzzles as long as they're sufficiently clued. (How you distinguish the lying parrot from the truth-telling one is, I think, a good example. If you don't know what I mean, pay attention to what the barkeep at the Micro-Groggery tells you when he gives you the kiddie grog.) However, if a puzzle is illogical and isn't clued...well, what can you do?
Consult a walkthrough, that's what.