Every stubborn odor has a source, and nothing works until it's gone. Smoke residue on walls and ceilings, pet urine in carpet padding, mildew behind a washer, or spoiled food in a forgotten freezer will keep producing smell no matter how much you spray.
Once the source is removed, the next step is cleaning the surfaces that absorbed the odor. Walls get washed, hard floors get scrubbed, and soft materials that can't be cleaned, like saturated carpet pad, usually need to be replaced.
Only then does treatment make sense. Professional fogging and deodorizing equipment pushes odor-neutralizing products into the air and into porous materials, where they break down odor molecules instead of covering them.
The result should be a space that smells like nothing at all. If an odor comes back after a few warm, humid days, part of the source was missed, and it's worth having a professional take another look.