E/I and P/J are the easiest for me to determine. S/N can become evident when you start a conversation. I have more trouble with T/F.
I think I can see if a person is a Judger or a Perceiver by looking at their appearance. Their shoes, cloths, hair and other accessory like purses, jewelery, bags etc. An other sign is how they maintain their belongings, like phones, mp3 players, laptops, books etc.
Judgers are more neat in their appearance and Perceivers are a bit more messy. Their cloths are more bright and colorful, and not always color coordinated. A fat Judger are better to hide his tummy then a Perceiver who might wear a tight old white t-shirt. Perceivers are more inclined to satisfy their need immediately.
If a man is running to catch the buss with full shopping bag in one hand and a hot dog in the other and he is wearing a withe "Hard Rock Cafe" t-shirt that is either too big or to small, red nylon shorts,old untied sneakers and black socks. Then I would say he is a Perceiver.
An other man is already waiting for the bus when it arrives, he is hungry as hell but waits till he comes home where the dinner is already defrosting in the fridge. He wears a black jacket because is has beige pants. He let all the other people get on board before him. He might be a Judger.
Actually, I don't think this is accurate at all. I know plenty of judgers who are sloppy dressers and who abuse their electronic devices.
I, on the other hand, and am a perciever who takes good care of my material possessions... up and until the time I lose them or give them away. However those which are still in my possession (like my old iPod I kept for 4 years, until I bought a new one and gave it away) are/were spotless and scratchless.
I am a
definite perceiver. I am also someone who dresses nicely. Do I prefer to be casual? Sure. But I can dress in business attire like nobody's business. =p
Just because I'm a P and pull clothes together in three minutes or less, does not mean that I am incapable of using that time to determine what looks good with what.
When I shop, I spend a lot of time - not because I particularly enjoy shopping (it is a pain), but because I care to only purchase clothes I am sure look good on me. People judge you based on the way you present yourself. I care to present a good image.
Am I the type who color-coordinates my closet and spazzes out over which shoes go with which skirt? No. Because I know I am capable of being creative and tasteful in a short period of time every morning when deciding what to wear.
My boss at my old office, before I decided to move for school, actually prefered to have me meet with new clients at first because she said she knew she could count on me to be well dressed and present a professional image.
I know plenty of other percievers who dress, if not snazzily, non-sloppily. I also know plenty of judgers who just don't care what they look like - or what people think of them.
So yeah. I still say you need to see someone in action to decide between P and J.