Question:
Vacuum cleaners? Canned air?

I disassembly the detector, remove the smoke chamber and clean it with an alcohol swab. We perform this routine on all detectors in a premises whenever we are called to service even one. This is either on a contract basis (X number of visits per year) or when there is a false from a single detector. Some companies are now making replacable smoke chambers which you toss out, inserting a new one in place of the used one. Regardless of the chamber design, I always clean the optics and the entire inside of the detector manually. It takes a few extra minutes per detector but the results are far fewer repeat visits.

Answer: There is a device made by Gemini in Sunnyvale, Ca. Which works very well and works on most Smoke Detectors,For testing and Sensitivities. Most Modern Microprocessor Based Higher End Fire alarm systems have the ability to list sensitivies when commanded and have the ability to tell you when they need to be cleaned.The best way to clean detectors is to Vacuum and not use Canned air. Induced Air well put dust and other media farther into the Detector ie behind lens assemblies, and into Ion chambers making the Detector Less Sensitive. So try cleaning it check the sensitivity if it falls within the Mfr window ie 1.5 to 3.5 this is a useable device.if not replace it.