is it true that evaporation lines are grayish in colour??

I've taken a test the other day and i swae i seen the faintest line but thought id take another one so i threw it in the bin but a few hours later i went to the toilet and seen it sitting in the bin with a dark positive... Can evaporation lines be so dark? I always thought they would have been faint but this test was as dark as the control line... I'm only asking because im freaking the heck out! I've not long had a baby and started on birth control a month ago and showing signs of pregnancy but they could also be signs from the pill so I'm not sure. TIA