Yes, dehydration definitely produces ketones.
Also, drinking alcohol and just eating a fatty meal can show as a "false positive." All in all, there are a lot of variables. Many of us here have found that they are just plain too unreliable.

I think the best thing to do is just follow your plan, and test now and then if you wish. Personally, I think the strips are a total waste of time and money. The results that count are the ones that comes from the scales, tape measure and mirror!

Rosebud