I'm not sure exactly where you are in the washroom, or what the timing is, here. My first thought is that you're in the stall, finishing up a poop, and you're wondering if you should look under the stall at the next guy.
My first question, assuming I'm somewhere close to the mark, is do you like watching other guys poop? If you do, this answer writes itself.
Because you asked for my advice, let's go with the angle that you're just a curious fellow. If that's the case, this is a privacy issue. Do you care about the other person's privacy? Privacy in general? Do you fear getting caught, the wide-eye between the crack, peering in at someone's most private of moments?
Scratch that. I just got the question. You're just referring to whether or not you should peek at your own dump. I see it, now.
This one's easy. The fact that you specifically mentioned that you were in a public toilet means that you're having an unwanted away game. This probably means a surprise poop, maybe even a wet one that caught you off guard. In this case: Do Not Look!
Short Answer: That's a weird phenomenon. Sometimes I get the thrust of the question wrong, but rarely do I realize halfway through. What a treat!
Note: I just had another thought. Is it possible that you're just entering the stall, wondering if you should see what the carnage is before you do a pre-sit flush? Perhaps...