I've only seen 2 walls that were not layed level. One, across the front of the house, folllowed grade 3-4 block high and really bothered me. The other, 2 block +cap, follwed the driveway pitch and did not look bad(pic below). But the way the house sat you would never see it head-on.
If they are not making it level, they should follow a mason line and make it straight, like this:
