Thaddaeus Ropac has called for an industry-wide "blacklist" of speculative collectors. However, informal versions of such a list has been around for some time (including websites that identify the sellers of "flipped" works that come up at public auction). However, such informal sanctions are very difficult to maintain. There is still some smoldering debate about the impact of "flipping," although the propensity for destructive impact on young artists' careers has been clearly demonstrated over the last couple of seasons. There is ambiguity, however, over exactly what market behaviors qualify as "flipping." An essential component of the definition appears to be, "something that other people do."