You dont think questioning your opponents line calls constitutes rude behavior? Inquiring as to what a line call was, is not the same thing as questioning a line call. When you ask for the second opinion after a call has been made, you are questioning the call. It's the same thing as asking "are you sure?", even if you ask it very softly.
Hold up. Now it sounds like you think players cannot question the accuracy of an opponent's line call at all, ever.
Could you please show me in the Code where it says you are not allowed to question your opponents' line calls?
The 2018 Code does not address it either way. Had the authors of the Code wished to preclude players for questioning line calls, that would have been a simple provision to put in the Code, no?
I know the Code used to contain a specific provision telling players how to question line calls. The 2008 version stated: "16. Opponent’s calls questioned. When a player genuinely doubts an opponent’s call, the player may ask: “Are you sure of your call?” If the opponent reaffirms that the ball was out, the call shall be accepted. If the opponent acknowledges uncertainty, the opponent loses the point. There shall be no further delay or discussion."
I recall that this provision was revised at some point to delete the "Are you sure of your call" language. This meant players could use whatever language they wanted (which I at the time thought was not a great idea).
The entire issue has been removed from the current Code. Questioning a line call, it appears, is neither authorized nor prohibited. Presumably, players can do whatever they want within Rule No. 1: "1. Courtesy is expected. Tennis is a game that requires cooperation and courtesy."
Now, I fail to see how refusing to answer a question posed about the accuracy of a line call in an appropriate tone amounts to "cooperation."
And just so you know . . . if I ask you about your partner's line call, one reason could be because I saw you call it in and change your mind, so I am absolutely giving you a chance to prove your integrity. But I am also doing what most people are doing when they question a line call -- serving notice that I saw that botched call, you didn't get away with it, and you two had better clean up your act.
Dick Kaufman says: Only one player in doubles needs to call the ball out. If the other player is silent it is assumed that that partner agreed with the call or could not determine the call. It is not really proper to ask the silent partner what they thought. You can ask the person who made the call nicely if they are sure.
As for Dick Kaufman, well . . . I am sure he is lovely but I couldn't find that statement or quote attributed to Dick Kaufman via google. I am very interested, so if you have a link, please share.
The USTA FAQs for officials do not address the subject, and I don't recall it in my roving official training classes.