It's important to remember that scratching is a natural, innate feline behaviour, so they should never be reprimanded for doing it, but they can be discouraged from doing it in inappropriate places, and encouraged to use appropriate objects. We cannot suppress our cat's natural, wild instincts!
Firstly, we need to understand that there are many reasons why cats scratch, which includes removal of the layered sheaths which compromise the effectiveness of their claws and also leaves behind an olfactory mark (the scent from their interdigital glands), as well as a visual mark which are communication devices which assists with modulation of social interactions. It's also a good way for the cats to exercise and stretch fully, including the muscles in their back and shoulders, relieve pent up emotions, and displacing of stress, excitement, frustration, and anticipation.
It's useful to take note about the type of objects your cat likes to scratch:
What material are they made from?
What texture is it?
Are they vertical or horizontal?
Are they on an incline?
How big are they?
Do they like variety?
Where are they currently scratching?
When do they tend to display the behaviour?
You want to try to mimic that object when providing an object for them to scratch on, and it's important that the object is about 1.5-2 times the length of the cat, to allow them to stretch fully. You also should provide a separate scratching post for each cat in the household, as scratching is a confident display, and also informs other cats who was there, and when the area was last scratched. In single cat households, the marks left by scratching provide them with a sense of familiarity and security.
You can use pheromone sprays, plugin, such as Feliway, or their own scent (capture it on some porous fabric from their faces), on the places where you want them to stop scratching, as cats don't like to claw mark where they facial mark, and these pheromone based products replicate the scents from facial marking. Never use pheromone based products on places where you want to encourage your cat to scratch.
There are products available to physically protect furniture, particularly the corners, however, if the cats are provided with appropriate scratching apparatus, and the above steps are taken, that generally resolves the problem. I would avoid the tape which is available, as this may be aversive for the cat, and therefore unethical, and I certainly would discourage anyone from using a spray bottle or any frightening techniques on any animal. It is also known that cats dislike citrus scents, but, again, I would avoid using anything like this if possible, as they may have a reaction, and please remember that many cleaning products and essential oils are incredibly toxic to cats and other animals,
And one final note-don't surrender one sofa to the cat, but reprimanded them for scratching your new sofa when you replace it. It's best to work on these habits so you and your cat can live harmoniously!