IF the flipper did the unpermitted work, you could sue her: in that case, she lied about the permits (either explicitly or by omission: by not stating that work was unpermitted) and such lies may well constitute fraud. However, if the prior owners (before the flipper) did the unpermitted work, you can't sue unless you can prove that even though she did not do the work, the flipper actually knew about the lack of permits: only if she knew about the issue and failed to disclose it might she be liable. But she is not required to "investigate"or look for problems, so if she herself did not know about the lack of permits because no one told her, she is not liable or responsible: in that case, she did nothing wrong.The inspector is most likely also not liable: inspectors do not have to pull permits or investigate who did the work or how it was done. If on a surface inspection (all they have to do; they don't open up walls to look under the surface) everything looks good, they did their job.