There is no way to tell. You are going to ask another contractor to attach to a guys work that he cannot see. Also the cost is going to be determined by how far into the walls/floors he has to go to get this done correctly. If the rough-in is off a few inches it can still work for you with simple trap extension tailpieces.

I know that because I missed the rough on one of my own sinks and used the extension tailpiece as well as a 45 to make it tie in. Of course that was my wife's fault because she changed the spec on the sink. She isn't hearing that though. Go figure!

"the contractor walked out."

Was the contractor or his direct employee/s performing all of the trades tasks?
Who pulled the permit, not who payed for the permit, who's signature is on the bottom line?
Do you have, in your possession, the on-site inspection record?
Was the contractor contracted to perform two or more trade functions?

"The contractor walked out"

I'm sorry to hear that. I've come into these situations as the back-up guy. There is always more to sort out than what it seems.

He was losing money on the job, and didn't see any way to make it right with you. I've never walked out on a job, but I've regretted taking on jobs.

"Some of it has to be reset as the height of the pipes is incorrect for the vanities"

That's a slap in the face. Vanities come in different heights. Standard height is 32", but many people like 36". I made a low one for my kids bathroom at 30" Who selected the vanity before the plumbing rough in was completed? Is there any way that the contractor got screwed by using a vanity that you selected and then ended up a different height than was expected?

Because the first contractor was losing money, it is likely that the project was not budgeted properly from the start. Or maybe the cost was right but then someone made a huge mistake, and now he is unwilling to eat the cost of the rework. If he believes that the mistake is your fault, and you don't see it that way, that could be the reason he walked.

At any rate, the cost is going to be more than the original budget. I'll take a wild guess: about 50% more labor. If there was money to be made, and the contractor is a legit business person, he'd still be on the job.

Thanks for the responses

He walked out because he was not being honest and we started to catch on to the stories and ask questions.
He pulled the main permit and had the subs pull the other mechanical permits- since he left we have taken over the permits and signed the necessary affidavit for workers comp etc.
It turned out the original affidavit he had put in our name and forged a signature - ie he did not have workers comp ... Though he was using some sort of HIC #.

The plumbing fixtures were here way before. the plumbing was roughed in and they knew it was 3 wall hung vanities. They were sitting in my a garage and they had all the specs they needed to set things correctly.

The original contract was a list of what would get done but not broken down - so we don't know how much was designated to each sub contractor.... Now we are trying to figure out what this mess will cost.

Thanks

You should start by contacting the subcontractors and asking if they have been paid in full, and getting a signed document saying so...
Otherwise, they can put a lien on your house to collect their payment; even if you "paid" the plumber to pay them.