When ttc DS (2) I took loads of tests and maybe had 1 or 2 evaps and even then only hours after the test was taken. I have taken loads of different tests this month thanks to a dodgy evapy Freedom test giving me false hope and I swear I've had evaps on them all, end. A FRER! I wish I could share the Clearblue one I had but there's some problem when I try to share photos it says no images available 
it looks like a really strong positive and popped up after about 5 minutes! Don't think it's a chemical as it was unlikely I'd conceive anyway this month (dtd too early but you know how you talk yourself into believing.) it's something I've noticed for a couple of months now and it's really pissing me off. If we go for ttc next month I won't be testing at all.