Can the Go/No-Go Association Task be faked?
I've never looked at the GNAT before but, even though it's just about as transparent as IAT, the critical thing making it difficult to fake bias is the deadlining.  In order to fake one would would have to respond in no-go trials where one would not and that also misrepresented their association.  That calculation would be difficult to do in the time window and possibly result in overall very high error rates.  I'm not a fan that they just throw out RTs.  Furthermore, calculating d' values does not by itself make a task better.

There's a general problem with many of these tasks in that the requested response is directly along the tested dimension.  What's implicit about that?  Asking you if bad goes with bug does not make for an implicit tests.  However, with something like the ALPS (Lebrecht et al 2009) you select an orthogonal dimension for the response (lexical decision in that case).  That seems much more like an implicit task and since people tend to be very response focused it makes it much less likely that subjects will pick up on how the test works and attempt to manipulate it.  You could also deadline that to make it even less likely that it's cheated.