Is it possible the spot you're seeing are light impressions, as in water spot stain impressions already in or on the paint?
If so, it could be when you're wiping the car off you're seeing these impressions or imprints as the wiping process will tend to reveal them to your eyes at the right angle in the right light.
That is they are not brand new spots being created but an existing mark in the paint?
Just a guess, if that's the case then applying a light cleansing lotion by hand should remove these spots and restore a clear, spot free finish.
A gentle hand-applied product would be,
Pinnacle Paintwork Cleansing Lotion
These kinds of spots happened to a Corvette I used in a video and the above product applied gently with a clean, soft foam applicator pad removed them easily and restored a very clear, glossy appearance to the paint. Then I re-sealed it with a paint sealant, Wolfgang Deep Gloss Paint Sealant I believe.
If they are actually spots in the clear layer and a light polishing like mentioned above doesn't work then you'll have to get more aggressive.
Some people have good luck using vinegar to wipe off mineral deposits but vinegar won't work if the paint is actually etched.
Here's an article on the topic,
What it means to remove swirls, scratches and water spots out of automotive clear coats
Here's a picture from the above article of a Type II Water Spot Etching
