loft

[glorybound]

How do you avoid this kind of bad geometry when using lofts?

[stef.thomas]

Are the corner vertices in your path welded?

[glorybound]

yes, they are welded.

[val2]

In the surface parameters/output select Patch. It should correct the problem.

Val

[Donald2B]

I always try to make sure that my path is located along the inner edge so that this exact problem doesn't happen. This will prevent wide shapes from folding into itself like your image shows. Works in most cases for me. Though in certain situation that doesn't always work.

[dlparisi]

Not a solution for lofts but the sweep modifier doesn't seem to have this problem for me.