... But it isn't symmetrical. Not sure what else you want to know.

So basically you are saying that the Poser system does not for every vertex in x>0 find a symmetric vertex in x<0 or vice-versa within the search tolerance. This could be the result of:

1 - position drift as could result from:

    a -  rounding off in the .obj file or

    b - morph corrections made but not made symmetric.

2 - the symmetric vertex simply not being there. This case 2 (not being there) again could be the result of:

    a - position drift (vertex intended to be at x=0.0, it's own mirror, but the vertex drifted outside Poser's search tolerance range)

    b - there is no paired vertex

1a, 1b, and 2a are solved with a morph. 2b would be topology error, which would be much more serious.