faint second line on ebay cheapie pregnancy tests

hello just wondering if anyone has any experience using the ebay cheapie home pregnancy tests???

I have done countless tests in the last few days but they all showed a shadow of a second line within 5 minutes then by 15 minutes it turns into a very very very light second line. 

however the instructions say to not read the tests after 15 mins.

could this be a pregnancy line or just evaporation lines? has anyone had this problem with the ebay hpt?