I have a question- I am a remodeler- we did a great custom kitchen remodel for a client- they were extremely difficult & unkind- all said and done it turned out to be the most gorgeous remodel so far- we took after shots of the pictures & out of spite it seems the homeowner said he did not want us to post the pictures on our website for privacy sake. We want to be able to do this- our work is extremely nice- would it be against the law to add it to our portfolio on our site?
I am not a lawyer; you should neither act nor refrain from acting on any information provided.
This situation is by no means clear cut. It brings up many other related questions that you should ask... the answers to each will depend on jurisdiction. I've offered my take and commenters are invited to point out how things may differ in their region.
Were you allowed to take the images? Yes, the homeowner allowed you on site with a camera and your rights as to image use were not limited in advance. Having a contract clause or property release would have cleared up any arguments in advance.
Have you violated someone's privacy? If anything allows that person to be identified from the picture then in many states it would be illegal to make that information public.
Are you libelling someone? If it looks even remotely as if you're trying to assign a viewpoint (such as an endorsement or suggesting they liked your work) then this is a very real risk. You know they were unhappy with your work which would also make penalties worse were you to lose.
How likely is it that legal action would happen? Unless they are lawyers or very rich it's likely that the cost of enforcing their rights is often prohibitive. Defending even a baseless suit would be very expensive although you may have insurance to cover it.
What's your 'best case' scenario? You 'win' and can publish a photo from a job for a homeowner who is unhappy with your work. A homeowner who is equally free to take your ad and run you down on social media in an industry which is often driven by recommendations.
TL;DR - I wouldn't publicise it if I were you. Having the right to take/use the pictures in your contracts from now on would clear some things up but maintaining a good image is more likely to be profitable than having the permission and upsetting people.
I also am not a lawyer, but it seems clear cut to me.
In the US, if you did not get a property release from the customer for commercial use of the image (i.e., permission to use the photos in a promotional context), they have grounds to sue you for invasion of privacy. You do not own the property on which the photos were taken and you do not have a right to use them commercially without the owner's permission. The implication of using the images to promote your business is that the owners of the property are endorsing/recommending your business. If they were difficult, unkind, and spiteful to you about your work, one can assume they do not wish to endorse or recommend you, and that is their right.
If you did get a property release or they don't sue you, you might be able to "get away" with it, but you are morally in the wrong--nobody is obligated to help promote your business just because they hired you--and particularly if they're not happy with your work. I would worry less about whether or not you can get away with using the photos on your website and worry more about providing the kind of service that results in customers who will happily endorse the work you did for them.
It's bad business practice everywhere to do something that antagonizes a customer.
And if you want people who probably see you as the problem (just as you see them as the problem) to be really angry, then use the image against their wishes.
Even if they're unhappy with your general work or approach to it, they might be happy enough with the end product to begrudgingly admit it to friends and relations, especially as time passes. You might get work from that. But if you antagonize them more, there is no chance of that and they might actively tell people not to ever use you. They might even sue you because they're angry (people do), and that would just cost you money and damage your reputation no matter what the outcome.
So leave it alone, and forget the law - this is about business common sense.