Beware! all ye who dive into the depths of next-generation sequencing data housed in The Cancer Genome Atlas. Lurking contamination may lead ye to false interpretations. Alas, such has happened in recent publications that state that human papillomavirus 18 is present in colorectal cancer and normal kidney tissue. However, these claims have been challenged by Paul Cantalupo and colleagues in a new publication. They show that HPV18 is not present in these samples but is, in fact, due to another case of HeLa contamination!