Anyone else using an ovulation saliva microscope?

I purchased a Fertility Focus saliva ovulation microscope, and I was wondering if anyone else has any experience with one of these (whether it's this brand or another one)? It seems pretty straightforward. I was playing around with it just to see if I could get it to work, and I tried it now (10:30 a.m.) after having coffee, eating, etc. It showed major ferning. I understand that you're to use it first thing in the morning before putting ANYTHING in your mouth (coffee, smoking, brushing teeth, etc.) My question is--how do these things (coffee, nicotine, etc.) affect the results? Do they cause it not to work properly, cause false positives (for ovulation), etc.?