Consider the following auction against competent opponents, not playing behind screens:
Do you double asking for a diamond lead? To me, it depends on what the alerts are and what 3♠ is. I want to know if declarer has a strong GF hand (no double), or is just invitational (doubling).
Yet, if I ask before the final pass, and don't double, partner might suspect me for this sort of hand. Other than an ethical partner making the natural lead from his hand on this auction, is the solution just to ask for every alert regardless of whether you intend to take action over it?
Benefits include:
Plus... it's free!