1) Lets start with a simple example, a football match, which is offered by every bookmaker you can imagine. There is breaking news, that team A will miss a lot of their players due to a flu. Odds are dropping like crazy in all bookmakers, but there is one bookmaker that is slow and has bad software.
I don't see anything wrong here. This is more of a level of service issue than anything. Especially so if they are consistently lagging in updating, this would be a glaring issue they would have to blatantly ignore. There could be any number of reasons for it, and would be something I expect them as a business operator to rectify and/or adapt to. I say that s this would be glaringly obvious to them, and not some random secret issue that could go unnoticed.
2) By accident you discover that a bookmaker allows to parlay 1X2 and Asian Handicap market, which is of course a software issue. So you could parlay home win with AHC -0.5 for all kind of matches, which will give you good value odds. Is it ok to parlay these two dependant bets ?
I don't wager often, so I don't get the logistics behind this. My take is that you run it once, make sure there is an exploit and prove it. You then contact their team and explain and prove it to them. Beyond that you are taking a hidden exploit and turning it into a scam. Not many people would be able to take advantage of it and if you attempt to be stealthy this could carry on for a long term.
3) Is it ok to take advantage of this software issue in general ? For $20 ? For $500k ? (Leave aside the fact, that LAngel played with "cheated" money).
No. I place this in the same category as #2. Try it prove it and then contact support to make them aware of it. If you go beyond that and attempt to game it for yourself you are knowingly attempting to turn an exploit into a scam.
4) Lets say I have a trading bot (in betting or crypto exchange) and this bot goes wild due to misprogramming and I lose loads of money. Are all these users filling my orders scammers, when it's obvious that these prices are wrong ?
In trading that would be on you, you are trusting your software to make decisions for you. No one is tricking it with a series of commands or events to make it do something outside of designed operation.
I feel the moment you discover something that is hidden and use this to manipulate the odds in your favor you are acting unethically and in bad faith. It crosses some lines and I would expect casinos and bookmakers to refuse service to individuals who abuse these hidden exploits without reporting them.
You have a flagged and heavily limited account in a bookmaker. Early odds come out, player A vs player B, 1.80 - 2.00. You want to bet on player B, but with higher odds. So with your flagged account you bet on player A multiple times max stake (because of the limit, you can't stake a lot though). Odds move of course, and are maybe 1.60 - 2.40 then. That is when a friend of you with unflagged/unlimited account places max bet on that 2.40.
Into what kind of category would that fall ? Exploit ? Scam ? Market manipulation ?
This depends. Are you taking a share of your friends profits. If so I feel this is 2 individuals manipulating and attempting to scam a bookmaker. If your friend happened to place a bet after you mentioned something along the lines of wishing you had been able to get those odds, then that's them using information for their own gain - not having participated in getting the odds manipulated.
Personally if they aren't offering the odds you want and can't find them elsewhere the spot doesn't exist. Fabricating it through betting and exploiting that using a different account makes this unethical imo. It's really no differnt than you just having an alt account to circumvent their TOS.