They missed a real opportunity for "Omelette Doom Fromage" there
But yeah, I'd wager too subtle. I'm also questioning now how much rats use smell for navigating their environments. I notice that my cat is a lot more smell oriented than I initially thought and I think it makes a big difference. Hard to tell though.
Humans are /extremely/ visual compared to other animals: this tends to make us underestimate the intelligence of other animals (when we use visual intelligence as a proxy for general intelligence) and miss out on smart uses of other senses entirely.
Rats are well-known for thwarting maze studies using things like fine sensitivity to slope, directional orientation using smell gradients across a room, or detecting the direction of researchers outside the maze based on micro-vibrations.
(Good book on the general topic of measuring animal intelligence: "Are We Smart Enough to Know How Smart Animals Are?" by Frans de Waal)
But yeah, I'd wager too subtle. I'm also questioning now how much rats use smell for navigating their environments. I notice that my cat is a lot more smell oriented than I initially thought and I think it makes a big difference. Hard to tell though.