The reason I ask is in my market appraisers often do not look up permits to determine a unit is legal if the unit appears to be legal.  

Get an appraisal.

You will probably be looking at 65% LTV max without a credit check, or appraisal. 

I have ordered Denise Evans book.I think I should also work to lower the taxes on any properties I obtain, not by rezoning but rather attempting to adjust the appraisal value. 

This lot was appraised for $40,000 and we purchased it for $1500 + $1300 in delinquent taxes and $750 in closing costs.

My flipping clients will often do that because the appraiser may not take it as a bedroom for financing purposes and buyers may see red flags if its an unpermitted bedroom.

I don’t mind paying the appraisal for it to be done.

It seems from what I have been reading in regards to ADUs, the appraisers / LA market has not giving it the value it caution air quotes " deserves

Even if I am fully aware of it, I shouldn't disclose it to seller, because I am not a licensed expert to do appraisals on properties and they could sue me, nullify and void contract in court, if I lied to them about their property values to get them sign a contract with me.

As I am coming to see it, even an experienced appraiser would struggle to advise here because of the subjective value to the limited pool of buyers (as noted by Kevin).