When is something considered so obscene as to be something that can be regulated despite the 1st Amendment guarantee to free speech? According to Justice Potter Stewart, "I know it when I see it." The same holds here.
I hate making hard and fast rules like this because the answer changes not only depending on the size and scope of your project, but I think it changes even down to the module level. Depending on what your method is doing, or what the class is supposed to represent, it's quite possible that 2 arguments is too many and is a symptom of too much coupling.
I would suggest that by asking the question in the first place, and qualifying your question as much as you did, that you really know all of this. The best solution here is not to rely on a hard and fast number, but instead look towards design reviews and code reviews among your peers to identify areas where you have low cohesion and tight coupling.
Never be afraid to show your colleagues your work. If you are afraid to, that's probably the bigger sign that something is wrong with your code, and that you already know it.
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
