I've had to point out where a treat was, too, after dropping it in front of them.
We have one cat that just stares at me a lot. She'll be real intent, like she is trying to determine if I'm friend or foe. But I have heard that vision isn't a dog or cats best sense, but rather smell and hearing. My mom has a dog, that when introduced to a new person will follow them around trying to sniff them, but run the second they turn around. She's also an occassional human behind sniffer. (Glad the cats don't try that.)
One thing I've noticed, dogs seem more interested in sniffing a cats behind, than cats seem towards sniffing a dogs rear.