I agree with all the posters who said that if you believe your ball was out, then you call it out. Baselines and service lines on the opposite side are impossible to call consistently correctly. But regarding sidelines, you can probably make the call as well as your opponent. Bottom line, be honest and call them as you see them. This minimizes second guessing, gains the respect of your opponents, and makes for a much more fun and fulfilling tennis experience
65 yrs, NTRP-based, 3.0 in Tennis League Network (tennisftlauderdale.com) Play mostly at Hardy Park near downtown Fort Lauderdale.