I'm not doing the above described scenario rather I've just started a discussion about this issue. Presently no one knows the answer (incl. advisors) because it's a grey area, indeed.
Your points are valid and good:
the income may be treated as capital gain in one country and personal income in another and one may say that I'm just managing my wealth while another may say that I'm trading and I should pay taxes.
As far as I know the US wouldn't care as it's capital gains according to their laws thus tax-free for non residents. Other countries prefer to differentiate between investments and speculative short term positions and they categorize the latter as personal income.
Huge grey area, that's why I'd like to hear what's your opinion about this as nowadays being a PT is pretty fashionable and relatively popular.
The short answer is you can have a wonderful run provided you stay under the radar. Nobody is going to monitor your internet usage on particular sites and ask why you spend so much time on broker's sites; well, North Korea might, but I'm not sure you could trade from there.
The detail;
1) don't live an ostentatious lifestyle.
2) don't piss off any locals
3) limit yourself to hookers, if it isn't going to get you arrested, and make sure you pay all that is asked of you. Make sure the guy next door with the fat wife doesn't get upset at the procession of nubile young women making their way to your door.
4) if you get a local girlfriend, on pain of death, don't piss her off.
5) limit your inward cash transfers to sundry withdrawals from ATMs.
If you can manage all the above, you should have a wonderful, carefree lifestyle free of direct taxes pretty much anyplace you go to. Some jurisdictions are difficult, just for being there a long time they ask how you survive. Avoid those places. I can't give you a list, do your own research. Singapore would, but then they wouldn't allow you to simply stay for a long time anyway.
