Did she use a second black market spell?
At the end of the fifth episode we know that Nerissa either got a black market glamour to make herself look like Faith or Faith got a black market glamour to make herself look like Nerissa in order to manipulate Bigby.
Now, with all the talk about how Bigby should have known Lily wasn't Snow White because he knows her scent so well, I'm wondering if she got a second black market spell to make Faith's head have Snow's natural scent (and possibly even mask the original Snow's scent from Bigby to throw him off the trail)? We know that she dumped the first head at the Woodlands, so she obviously dumped the second as well. She was doing this to motivate Bigby to investigate, and what better way to get him to investigate than to have Bigby convinced that Snow is dead. If she convinced someone like Greenleaf to give her a glamour to bring down the crooked man for murdering Faith and Lily, it certainly would make sense that she'd be able to get another spell to help convince Bigby further.