Like any other reality shows, Project Runway has its villains:
Season 1 saw Wendy Pepper (a 40-something mom from Middleburg, Virginia). I think the biggest mistake of Wendy is having a "strategy" that involves feigning closeness with fellow designers and learning their weaknesses in the hope of using those weaknesses later in the show. Had she been in Survivor, that strategy would have worked but hey, this is a reality show that judges based on talent and creativity. It's not surprising that viewers and other contestants detest her. She went on to finish third in the final runway show.
Season 2 saw Santino Rice (a designer from Los Angeles) who has a very strong point of view - in design and attitude. He argued very strongly with Nina Garcia (fashion editor of Elle magazine) on the lingerie collection challenge. His works are edgy but sometimes (especially during the middle of the series) goes beyond the boundary of taste and commercial viability. He went on to finish third in the final runway show (behind Chloe Dao and cutie Daniel Vosovic). I think his biggest mistake is losing his point of view for his collection. He was put there on the top 3 because of his point of view as a fashion designer but he lost so much of his personality in the final show that it was boring. Also, without the rags of clothes in his clothes, the wrong fit of the garments was readily apparent.
Season 3 had Jeffrey Sabelia and Zuleman something. Jeffrey won the show while Zuleman got eliminated in the middle episodes. Jeffrey is not as villainous as Wendy and Santino but I think he lacks tact and patience. Zuleman has a very strong personality which sometimes conflicted with fellow designers.
Season 4 had Christian Siriano. He's the least villainous of all and the most talented (but needs refinement in taste). He won season 4 (which I believe handsome Rami Kashou should have won). Christian is more of annoying and tactless rather than villainous.
Except for Christian, I believe the common thread between these people are the desperation (often coupled with questionable talent) to get to Bryant Park. For Santino and Jeffrey, I understand where they're coming from: Santino had a really bad time as a designer and went serious depression after his collection (prior to Project Runway) bombed. Jeffrey Sabelia was a drug addict in his younger days and is mending his ways. For Wendy, I believe her reason is that she is the oldest among the designers and needs the chance really badly in order to get noticed before her time ends. Still this is no reason not to be nice with other designers.
Of course I also have my favorites: Kara Saun (so talented, impeccable finishing) of season 1; cutie Daniel Vosovic (season 2); humble Mychael Knight (season 3); and handsome Rami Kashou of season 4.