Most Helpful Guy
I'm not sure what you consider fancy sandals. If it is a sandal type of outfit, I like the flat thong styles that are popular or other sandals if they have a strap across the back. Flipflops and slides or mules say lazy to me. If it's a boot style, I like the combat / oxford style boots with a 2-3 inch heel. Formal needs a stiletto heel pump or sandal.
Shoes that are an immediate turn off: crocs, toms, most flipflops, ballet flats, huge platforms, and any of the wedge-platform sandals that have the straps that go to the ground. Especially if the wedge part is even remotely the same color as her foot. From a distance, it makes her look like her feet are 6 inches thick.