Evap lines can either look like the following:
1. An indent.
2. A shadow.
3. Grayish in color (aka colorless).
4. Skinny.
A true positive would be the following:
1. If you're using a test with red dye like First Response for example, the second line would be a little bit lighter than the first line, a little thicker than the line would be if it were to be an evap line. All lines are different though, depending on the test. If you use a $ tree test, if you notice the first line is very red & THICK, so the second line should be thick (maybe just a tad bit thinner than the first but still THICK), & about the same color as the first line.
Basically, a positive is just lighter than the first line. You can go to
PeeOnAStick.com & it'll show you how evaps look like & how positives look like. Also, if the box says do not look at the test after 10 minutes because it'll show an invalid reading then make sure that line is appearing before 10 minutes, but also don't count on that all the time because I've had evaps that shown up literally after 2 minutes of testing & I really thought it was a positive. I was also using $ tree ones & the first test showed a gray line where the second line if it were positive would have been, so I took another the following day & it was actually PINK, close to the color of the first line & it turned out to be an evap because I got AF soon after & was never pregnant. I even went to the ER to be sure. I came home & played with the test. After opening it up & analyzing the frigging thing I decided to scrape off the second line thinking maybe if it were a positive the line would've still been under it, or even an outline or whatever, but nothing was there. It was definitely an evap. Some tests I'm very weary of.
Deal with EPT or Clear Blue Easy, even the Digital is good because there's no mistaken it. It's either a YES/No, or Pregnant/Not Pregnant. Good luck!