How can you tell if noise is dirt or static?

I've been listening to a lot of LPs lately, and the weather has been dry so I have a humidifer running all day long. However, some records (older ones) that I've picked up used still have a lot of ticks and pops. How do you know if the issue is being caused by a static charge on the vinyl, or if it's dirt that is still in the grooves? I've cleaned all records using a Spin-Clean, but I plan on picking up a steam cleaning unit today to give that a try....
Are you also using a Zerostat? That generally helps.
What are you doing for cleaning?
No I'm not using a zero stat. For cleaning I just adopted a steam cleaning method, but I've only used that on one LP so far. I have a Spin-Clean unit that I use to clean the records, along with some hand scrubbing. I was drying them with a microfiber cloth, but I think that was giving them a static charge so I began to air dry them. That seems to have made an improvement.
Play the song twice. Odds are a static charge won't release at the exact same spot twice.
If it happens in the same spot again, it's dirt.