What to ask, and why
Will half my wall get torn open looking for it?
It shouldn't. The goal is the smallest opening possible. Odor tracing and access through attics, crawlspaces, vents, or outlet boxes come first; if a cut is needed, it should be small and patchable.
The animal was removed but it still smells. Why?
Fluids and residue soak into insulation, framing, and subfloor. Removing the carcass isn't the end; those materials need to be treated or replaced.
Will this keep happening?
Not if entry points are sealed. That's work for a pest or wildlife professional, and it's worth doing right after the odor is resolved.
Is the smell in my condo coming from my neighbor?
It can be. If tracing points to a shared wall or ceiling, involve your HOA or building manager so the source unit can be checked.
Will air fresheners take care of it?
No. Fragrance only covers the smell for a while. Ask any provider whether synthetic fragrances will be used, and look for one that treats the residue causing the smell.