The problem with getting no spot from a much better player is that you do not not what game you are getting from the much better player! So how do you judge if you are getting better? Many players, for cash, will play just good enough to keep their hand in your wallet - better to force their best game with the right spot and then judge your improvement by forcing them over them to reduce the spot- much better way to judge your own improvement. From my own experience.
Unfortunately I think you're right here. North American Pool in of itself is populated with players that are generally looking to take advantage of others. I make the distinction of North America simply because I have no exposure beyond this continent, so I really can't comment on the attitude aboard.
Speaking for myself, I can honestly say that the ability of an equally matched or lesser the opponent does not matter to me, however with these players the bet does. These players will normally not get my 'best' effort if I'm indifferent to losing the bet. I view these situations as practice time, and will take risks in an effort to expand my abilities within game play. Once the wager reaches a 'ouch that sucks' level, I will then pull in the reins and take it seriously. This raises a moral issue for me, as I will not accept a large wager match with a drastically lesser local player. For these notably lesser players, I flat out ask what kind of match they want and do my best to oblige. It's actually quite a sad state of affairs really. I've been back in the game seriously for a few years now, and I still have guys refusing my initial requests for a game because they think they 'must' put up a large bet just to play me.
Now if I'm matching up against someone who is even just perceived as stronger then I am, then once again, the bet does not matter. It's all guns blazing... I want that win, and I want it without a handicap in my favour.
Personally..., I think if someone wants to gauge their own development. They should do so in a tournament format. In the world of match play gambling, there's too many other things going on to know if you're ever getting a legit game.