Prospective client already has a site but it's ugly

I've noticed that alot of dog grooming businesses have super ugly sites and I would love to make them a new one. But I'm not sure how to convince them especially if most of their work does not come via the website.

What are some black hat methods to convince them otherwise? I have thought about just straight up undercutting however much they are paying for their site atm especially if they are using something like squarespace.

You are looking for a blackhat tactic to convince your client to redo a site they're not really using?

You don't need to act against your client's best interest, just to offer a way of turning their site into a consistent source of clients, and just then offer an honest suggestion to redesign it to increase the conversion rate.

Test a few low cost LP designs before you offer to redo everything. Use data as your main selling point and be able to showcase how long it should take the additional revenue from the improved conversion rate to cover the cost of the redesign and development.