Context:
I heard this conversation between a woman and a man. The woman asked the man why in his country many men wear the earring and he explained that it's either because they like to wear it or maybe because they are gay. The woman said that she doesn't like it because it looks strange and the man replied "I think so, that's why I would never wear it". The woman then said "ты вообще молодец".
So, was that sarcasm? What's the exact meaning of ты вообще молодец?
So, was that sarcasm?
That fully depends upon a context / intonation. Could be a sarcasm, but also could be a praise.
What's the exact meaning of ты вообще молодец?
Just as is: "you're really a good fellow".
In the described context the reply "ты вообще молодец" could be:
Confirmation of the man's previous statement
In this case the phrase could get translated like 'You are down with it', 'You rock', implying that the woman really believes the man would do (or normally, usually = вообще does ) the right thing, and she approves his taste
Mockery of the man's statement, disbelieve or reaction on his assertion
Here the usage of the phrase is rather irony than sarcasm. This meaning is mainly expressed by the word вообще that, besides the direct meaning of 'in general', can stand for both good and bad, negative or positive emotional connotation, much like the English 'Great!'. A common usage is '(Ну) вообще!' (Oh great! Perfect!). And we can add whatever we need to it to narrow to the subject: Да она вообще спец! Ну он вообще Паганини...
I think, this should be explained word by word. "Ты" is "you", that's clear and easy. "Молодец" with the accent placed on the last vowel primarily means "a good person", it is kinda frequently used to praise someone. The phrase "Ты молодец!" means "You are good!" or "Your effort was good", or "You performed well". The same letters with accent placed on the first vowel is used to describe a man (not a woman!) who looks brave and strong, and is very archaic. Frequently used in tales as "добрый молодец" to describe the epic protagonist, the word "добрый" meaning more "хороший" ("good") than "добрый" ("kind") in this case.. Don't mistake one word for another, though.
"Вообще" is a more complicated word with meanings changing strongly from context to context. Check this for a lot of info. In this particular case it is used to intensify the sentence, the meaning could be explained as "most of the time", "absolutely".
As mentioned by @Matt already, it is unclear if it was sarcasm, you can only tell this by context and intonation. Hope that it helps.
