I think snakes can have a real problem with mites (and beardies occasionally) so that may be the herp those products are geared to. I wouldn't worry about your cham. Any mites that happen to come in on a plant will not harm the cham nor should any that come in on feeders (if they are grain mites from the feeders food or bedding).
If you check out some snake forums you'll see many threads/posts on mite remedies.
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Chameleon Help & Resource Info
1.0 Nosy Be Panther Chameleon - Cyrus
0.1 Veiled Chameleon - Luna. She's now hanging from her big jungle gym in the sky
1.0 Beardie - Darwin
1.1.1 Side-blotched lizards - Ana and Stan
0.2 felines - Kyndra and Lita
0.1 African Clawed Frog - Skippy
0.1 Chilean Rose Hair Tarantula - Rosa Leigh, Died 4/21/06 
0.1 Goliath Bird-Eater Tarantula - Natasha, donated to science 4/4/06
?.? Pinktoe Tarantula - no name yet