As far as DW being detected in her room, I think someone would have to linger to leave a scent. As Redlipstick reminded us from the transcripts, he was covered from head to toe from a cap on his head to the boots on his feet. I don't believe he would have hung around.
As to the MH. By the time the police entered with the dogs the comforter(s) had been removed and cleaned. I would think the comforter would have held the scent since her fingerprints were found near the bed. DW also tells the police himself that after their visit to his house Monday morning he sat down at his computer to do some stuff, then headed out to the MH with vacuum to "find his cell phone". I think it possible that the comforters not in there plus any cleaning he self-admittedly did may mute or outright eliminate her scent.
1.Had the dogs used by FBI and SDLE found Westerfield scent in Danielle's room or Danielle's scent inside the MH, do you think they would have used it as proof DW was in her room or Danielle in his MH?
2.If they had presented this as evidence(prosecution)in trial would you believed it was proof of presence in bedroom/MH?
You see I don't like the fiber stuff but it's there as evidence and I have to recognize it.