Yeah, as Dave says, it depends. Do your research, as you would for any other product.
I bought some 3D-printed part, heads mostly, through the now-defunct Shapeways. I was happy with the product. Shapeways was really a marketplace or distributor for the individual 3D sculptors, so there was one level of potential difference between any two products-who was the sculptor? Also, many products were available in 2 levels of quality. The basic level could be rough, for example, and need more cleanup. The advanced level was generally a very fine print that needed little or no cleanup. To the buyer, it really depended on the subject, his particular need, and how much work he was willing to do, to decide which to choose, if the selection was available. Mine were 54mm heads, so I chose the advanced level to reduce the amount of cleanup I needed.
There is so much variety out there, that you just need to do your research, as I said to open this reply.
Hope that helps!
Best regards,
Brad