Yep! There are some people that would argue that he cleaned. IMO there is just no way that he could have cleaned all traces of DNA in his trailer. We all saw the video and the pictures of his place, I just don't believe that to be the case.
They never argued that theory at Steven's trial though, they actually dropped some charges when Brendan wouldn't testify. It was mentioned during Brendan's trial though, and was part of his "confession", just no corroborating evidence to go with it, like DNA on the bed, marks on the headboard, etc. There is a picture of Steven's bed and headboard... there is a layer of dust on it, how in the world was Teresa tied to that and the dust wasn't disturbed? Or how was it cleaned and the dust replaced? It's things like that that make it so I just cannot get on board with that theory at all.
I also think it's really sad that TH's family was and has been told that that is what happened and those were her final moments with no evidence to back that up other than a State theory and a confession riddled with inaccuracies. JMO
ETA: I think I have also read the theory that Steven covered everything in plastic first