I don't trust them at all. I spent a lot of time "testing" for nitrites during cycling and thinking I was still in the ammonia phase until I switched to liquid tests and realized my nitrites were out of control and my cycle was nearly over...
25 gallon community - cardinal tetras, cories, honey gourami, GBR
10 gallon - betta, otos, ADFs
2.5 gallon betta tank
2.5 gallon RCS tank