I can suspend plenty of disbelief about the effectiveness of superheroes' flimsy masks / clark-kent glasses. But Lance, on Arrow, (a) knows for a fact that his daughter is the Canary, (b) knows that the Canary and the Arrow are inseparable, and (c) also knows that his daughter and Oliver are inseparable. But supposedly he can't guess Ollie's secret identity. Dude's got problems.