Every time someone is trying to convince you
Every time someone is trying to convince you they don’t read your Twitter, there’s a test for everyone saying so… and they fail it ;-)
As you can’t keep everyone happy and agree with every side of every discussion, every now and then you’d post something that someone somewhere might not agree with. If that person happens to be one of the people to tell you (why?) that they DO NOT follow you on any social network actively then they’re surely going to mention, respond or just walk and tell you (as if saying somewhat proves that they don’t follow you online).
The fact of the matter is that people are just too curious.