I bought an el cheapo Texsport tent once. The problem with that POS was that the PU coating was too thin. A 5-minute, fairly intense garden hose test didn't reveal any flaws, but a continuous, overnight rain totally overwhelmed the thin PU coating and soaked right into the tent. Luckily, the overnight rain test was in my own backyard and I didn't sleep inside. It took a couple of cotton kitchen towels to soak up the lake inside!