Silly question: At home depot they sell scotts red & white bags labeled top soil. Is that considered good compost?
No, even the stuff labeled "Compost" at HD and the other box stores isn't very good compost. The best place to buy compost is at a local nursery or garden center. Buy it in bulk. It's much less expensive that way.
I agree 100%. If you want compost and find it at a nursery, check the fragrance. It should smell very fresh. Also when you put a little in your hand, you should not see any tiny crystals of sand. Sometimes sand is used as a filler. If you see some, the cost should be considerably discounted.
What are you using it for?
I was going to use it as a top dressing over the lawn after seeding. My local nursery sells a compost/peat moss mixture. Is that any good?
The reason people use topdressing after seeding is because they are not aware of using a roller. The purpose of the topdressing is to ensure good seed-to-soil contact. If you roll the seed down with a water fillable roller, you get the same effect.
If you are still going to use topdressing, then any topdressing will work. You don't need much at all. Apply at a rate of 2.7 (or 3) cubic feet per 100 square feet.