Why is it when using zremesher on symmetrical objects the mesh ends up slanted ?
What do you mean?
Can you post a screenshot?
Are you in Perspective view with a very wide angle of view?
Just tried to make an example and it’s not doing it. Many times with either a cylindrical / box / sphere, when I remesh instead of edges being (initially) straight across either x/y/z, the edges start slanting. Also having problems with wonky edge loops.
Is there a method of keeping edges straight / uniform ?
This for example was straight across …

Before you zremesh, make sure you activate symmetry on x or z axis (or both)

What if there is slight differences on an object ?
If there’s a slight difference, then it’s not symmetrical by definition… and you’ll need to adjust the zremesher settings until you come up with a good result.
If you NEED it to be symmetrical, you can mirror and weld before zremeshing.
Ok, thanks.