Pricing Bond using Different Different Benchmark and Spreads

Maybe there’s a disconnect in my understanding but I understand that you can price a bond off of different benchmarks and quote it under different spreads (T spread, G spread, Z spread), but this would give different prices and yields right?

How does an investor know if a bond he’s buying is a good buy or not if it can be quoted under different conventions?

I believe that you’re putting the proverbial cart before the horse.

In the real world, the market decides on a price for a bond (and yield). Given that price, the various spreads can be calculated, and they will be consistent. The market doesn’t start by deciding on spreads (and hoping that they’ll give the same price/yield).

There are many situations and calculations given on the CFA exam that would never arise in the real world; they’re given to determine whether the candidates understand the concepts, not because they mimic the way that the world does things.