When studies examine true effects, they generate right-skewed p-curves, distributions of statistically significant results ith more low (.01 s) than high (.04 s) p values. What else can cause a right-skewed p-curve? First, we consider the possibility hat researchers report only the smallest significant p value (as conjectured by Ulrich & Miller, 2015), concluding that it is a ery uncommon problem. We then consider more common problems, including (a) p-curvers selecting the wrong p values, (b) fake data, c) honest errors, and (d) ambitiously p-hacked (beyond p = .05) results. We evaluate the impact of these common problems on the alidity of p-curve analysis, and provide practical solutions that substantially increase its robustness.