T2 relaxation decay curves from in vivo human brain tissue are rarely mono-exponential. Partial volume averaging further reduces the chance of mono-exponential decay. Moreover, the parameters derived from few-echo mono-exponential fits change with the measurement echo times and have the largest possible variance. In this note, multi-exponential fits to 32-echo relaxation decay curves from in vivo human brain are used to design simulations (where the truth is known) to demonstrate the pitfalls of few-echo mono-exponential interpretations.