Here's the good news for contractors, semi-bad news for guys like me...
There are very few "BAD" blades anymore, at least from major retailers. However, on the other side of the coin there are more "Better" blades available at reasonable cost.
It really comes down to how often you use a saw, and how specific the material is. If you're cutting nothing but old concrete a couple times a month, a cheepie is perfect, and will last. If you're cutting thin veneer, high PSI pavers, then you need a better blade.