In a few cases, I've found the Niednagel approach with sports is a good indicator. But this requires another letter. For example, SFs are known for gross motor skills, and I know a number of ESFP guys who play sports, are not deep thinkers, great fun to be around, and go to the gym or play basketball regularly. Great guys, but I don't introduce topics with them other than women, sports, and what time the party starts. But I'd much rather hang out with them than another ENTP who wants to argue some point with me. SFPs are often some of the best dancers, a lot of fun at a club.
STs have good fine motor skills according to Niednagel, and I've found handymen and athletes with good hand-eye are often this type.
But just by listening to people talk, probably can't tell over half the time. There are hardcore Ss I can pick out easily, and people with unconventional points of view in business or politics are often NTs.
Per some of the other comments, interest in reading could be a good indicator. Many T's like me read mostly nonfiction. I know some ExTJ guys, and the ones who want to discuss ideas they've read that don't relate directly to their careers seem to be N's, while the Ss seem to read books they can apply now to their work.
One of the things I hate is business jargon. I've noticed Ns typically create it, while Ss overuse it as a way to express bs ideas in a way that sounds concrete. So it's not an N/S indicator, but a skeptical N will be able to grasp the underlying concept and express it in plain English, while a skeptical S will just call the whole thing bs.