The shirt missed its mark

The ‘wear the shirt’ figurative expression means to deeply commit to something, show loyalty to a cause, and fully embrace its values and goals. 

In this case, the literal meaning of ‘wear the shirt’ is not aligning accurately with what the shirt itself is implying. The shirt is being worn, sure, but its message is not being internalized. 

This person is sending a message and letting everyone know they are trying to quit smoking but are not really engaging in the practices required to actually quit. One thing is for sure: we can say that they tried and, maybe, are just really good at convincing people to give them cigarettes with arguments, no matter what their shirt says.