Legal Question in Real Estate Law in California

The case seems pretty weak to me because the seller's claim sounds very unspecific and also relating to a matter or matters that were clearly visible. In order to prove fraudulent misrepresentation, you must show that the seller deliberately misstated (or concealed) a material fact, and that you reasonably relied upon the misrepresented or concealed fact. These don't sound like hidden defects, nor does it sound as though the seller said anything about quality. I'm not saying your case cannot be won, just that it is not particularly strong.

Further, as to the per diem, how was the seller successful in adding this onto the price you had to pay? Generally, the price for real property is set forth in the contract. Did it also include per diem? More frequently, it goes the other way - the seller doesn't vacate by the closing date, and has to pay rent to the buyer.

I'd encourage you to negotiate this with the seller and the seller's broker and try to arrive at an out-of-court settlement; your prospect in court is that your legal fees will exceed your potential recovery, if any.