I am really terrible at calling serves out, especially fast ones.
I will play an entire match thinking I am calling serves accurately on my opponent only to hear my teammate berate me after the match claiming half the serves I played were out.
Occasionally I have had my opponents call their own serve out and I have never argued with them and just let them take a second serve.
Gamma Tour 320X, a marvelous raqcuet on the cheap! Donnay X-Hybrid a true hidden (and cheap) gem of a hybrid.