I don't expect to be able to tell exactly what the finished beer will taste like from the sample. However if I detect something that seems off from the beginning I know it didn't happen after dry hopping or transferring to the keg or after carbonation. Which helps determine where in my process and issue could have come from. I do keep an open mind that flavor will change as the process continues. But if I taste the same thing in the finished beer as I did in one of the samples then I know where to start my problem solving.