I don't understand what exploitation is. To me, the question is "am I in a better situation now than I was before" is way more important than anything else. I am concerned with maximizing prosperity for everyone, not what's fair and what's non-exploitative, who profit more, how equal is our society, etc.
Well, slave owners make tons of profit. You would tolerate slavery in your society?
If Adam wants a person to live in his basement, that has some value which would make the rent cheaper for Bob. But Adam doesn't want someone living in his basement - he does however want money. They will come to an agreement at the point where Adam gets enough money to part with his basement, which he doesn't want to do. Again, if he does, rent very well may come close to minimum required.
Bob should compensate Adam for supplies and labor, no doubt. However, Adam does not do any labor or contribute any supplies in simply letting Bob occupy the basement. Why should Adam get something for nothing?
Carp: Thanks for your thoughtful responses. For the record, I have nothing against landlords, employers, and lenders as people. All the ones that I've met seem very nice. You seem nice, too. For the most part, exploiters operate under the coercion of their own exploiters. Exploiting others may make them comfortable, but it will not make them free, kind of like kapos. Even though many kapos weren't very nice prior to their promotion, they got ahead by exploiting others on the order of their own exploiters.
You mentioned some of the problems that crop up in cooperative situations. These problems happen in exploitative ones, too. In the case of an apartment building, residents, whether they own their dwellings or not, can disrupt each other. In an exploitative situation, a the plaintiff resident will appeal to the landlord who may or may not use his authority to fix or at least eliminate its symptoms. The landlord's solution may not satisfy the residents, but that's irrelevant. All bets are off if the resident has a dispute with the landlord. In a cooperative situation, residents will have to work things out amongst themselves. Of course they can try to do the same in an exploitative situation, but the landlord can rule out whatever solution they come up with. Ten thousand Internets to whomever can guess what solution I came with for my neighbor's disruptions.
As Bitcoin pioneers, many of us may have a choice between engaging in exploitative relationships or cooperative ones. I encourage everyone to choose the cooperative path and not seek undeserved positions of power over one another.