Archaeologists’ newfound ability to access vast digital collections creates opportunities but also presents challenges when those collections are from varied sources, including public institutions and private collectors. We illustrate these challenges by comparing two analyses of gender in Mimbres pottery images. Both analyses used the same procedures, but one included material in private collections, while the second drew on a smaller but more controlled sample. Gender distinctions and division of labor were revealed by the first analysis, but the results were not duplicated in the reanalysis using the controlled sample. We consider reasons for the difference, addressing how collectors’ interests may skew collections and suggesting that some particularly desirable Mimbres pottery designs were created using modern paint. The article concludes with recommendations for how archaeologists can best use mixed collections. These include considering how collections might be skewed and designing analyses to counterbalance likely issues, more chemical analyses with representative samples to gauge the extent of modern manipulation of Mimbres vessels, collecting data on the provenance (i.e., collection history) of material in order to try to trace the likelihood of post-excavation modifications, and studying the process of collecting as a means of understanding the authenticity of artifacts.