Best way is to use your own artistic senses. Do the faces look like normal human shaped faces, or do too many look on the chubby side? Do doors seem a little wide, not as tall as they should be? Compare to real life things, the game has a car? Look up a real picture of the car. There are no extra NTSC/PAL notes in terms of the TOSEC collection, for the most part The only time they would note NTSC/PAL versions were on rare occasions there were completely separate NTSC/PAL releases. Example, Lemmings had a separate NTSC release for those machines, and a PAL release, Pinball Dreams is another... Arkanoid. These were altered versions of the game for those machines. A game could get released in PAL and NTSC, but may not have been altered in any way because they run in both modes. The above examples had issues, I believe, and thus had completely separate versions. Pinball Dreams was a pure PAL designed 320x256 game and had to be altered so you could still see the score in the NTSC version.
But for the most part 99% of NTSC designed games will run in PAL mode, just not at the correct speed/aspect ratio. Opposite is not so true, quite a few PAL designed games simply won't run on an NTSC system, which is why you have an online prevailing (and false) wisdom that would like everyone to believe there were never any NTSC releases. Oh, there were tons of them, and I'll debate anyone on how much better those games are.
Anyway, I do my best to show anything I do in the designed mode. I have a PAL/NTSC switch for my 500, to switch between them. For the most part I can figure out what mode a game is designed for, simply knowing the games overall history and looking at the game. If I have doubts, I'll look up the game on the hall of light Amiga database to see if I can get insights on the games origin countries. Made in America/Canada? NTSC all the way. Was it a port of an original Japanese arcade game? Probably also NTSC, even if the game itself was designed in Europe, because they were likely using the original art assets. Power Drift is an example of that, made in Europe but looks and plays best in NTSC.
What's the genre? Not the greatest playing platformer? Probably a European budget release, meant for PAL mode, even if that game does not fill the entire PAL screen. Sometimes PAL designed games would use NTSC graphics mode hoping for an American release. RPG/Strategy/Simulation? Not guaranteed, but most likely NTSC. Port of a DOS game? NTSC.
Know your companies. Sierra/LucasArts/Cinamaware/Microprose/EA - More than likely NTSC. Look up old reviews from magazines back in the day, who had the 1st look? Mostly just play the game in either mode. The worst thing Amiga fans do is make people afraid of NTSC machines. They don't understand the wealth of not only American games, but in the software category, word processors or whatever, that stuff was overwhelmingly NTSC designed.
A moment of silence for another soul convinced into getting a PAL Amiga they may not have needed. Did they also tell you you'd need weird power converters for the thing? You don't, a regular NTSC power supply works perfectly fine in a PAL Amiga vice-versa. Depending on your motherboard type and Agnus cheap, you may be able to install a switch like I have, or use a software switcher to go between the modes. Kickstart 3.0 and higher have a built in software switch that can be accessed on bootup.
Not filling the entire screen is something that should cause you to think about it all, but does not guarantee it's not PAL. Another World was released in America as Out of This World, separately titled, but the game itself was designed in Europe with 320x200 NTSC graphics mode. It works, and it works well on an NTSC Amiga, but the designer was looking at it all in that weird widescreen black boarder look. In NTSC the doors look way too tall, the characters just a bit too skinny, etc.
Some will tell you to look for objects like circles, they are wrong because often times games were designed in Deluxe Paint, where the circle in NTSC mode was never perfect, not with the circle tool anyway. Could still make them more accurate yourself by using the free form circular tool, but there are a lot of games that might not have perfect circles but are still NTSC.
Look for people and real life objects (not circles) that you have experience with. A big red flag for me is if there are televisions/monitors in the game. Does a 1980's Amiga game look surprisingly ahead of its time by having a television that looks widescreen? Then you're running an NTSC game in PAL mode. Look up the designer/publisher, though that's not always perfect. Port? Look up the original version. When in doubt, switch your Amiga into both modes, feel them out. But no, there are no current notes when it comes to that stuff. If you have a PAL Amiga and come into difficulty actually running software on your Amiga, it's more than likely a crack problem. Try to find a source for games/software with multiple versions, perhaps without a crack. It's unlikely you'll find too many NTSC designed games that simply will not run, most will. Arkanoid I believe is an example of an NTSC designed game that simply will not run in PAL mode, and thus had a separate PAL release, but almost anything designed in NTSC mode, which was graphically 320x200 would easily fit into PAL mode, which was 320x256, hence the black bars making it look widescreen, because 56 pixels are not used on a PAL setup.
Note music tempos if a port. Sierra games and some LucasArts stuff will not only have the graphics look stretched in PAL, the soundtracks can be noticeably slower compared to their original DOS versions, but are correct in NTSC. Chances are great if you're getting a file online that it's probably from a PAL source, AKA a cracking group. I've seen NTSC designed games get a PAL crack and then not run on NTSC machines despite being made in America! This is simply due to the prevalence of pirated European software getting out there, it's not a statement on how many NTSC titles there are. If you see black everywhere, if it looks widescreen, start looking. Seem a little too slow? Faces/objects/etc look a little too wide? Designed by an American company or originally a port from America? Probably NTSC stuff then, though it most likely should run on a PAL Amiga, just not as designed.
Well designed PAL games would hopefully utilize the full PAL resolution of 320x256, and thus be in full screen, but that's not a guarantee, and lots of PAL designed games actually do look and run right in that widescreen black bars look. So unfortunately, while there are tips that should help you in most situations, there's nothing I can point you to that would tell you matter of factly.