Mike is correct, but there are exceptions, when I first learned about Subject to, my wife and I went to a week long seminar on Creative Financing about 17 years ago. Subject 2 was just one of many topics.
During that week I was calling some of my contacts every evening, flew back on a Saturday, and Sunday afternoon I had 4 Properties under contract using Subject to from a landlord who did not want to be in the business anymore. Referral from another Investor.
Marketing is the key, anyone looking to just have someone taking over the payments on their loan do not know to look for you, you have to have a marketing plan.
When I wrote my Book on Subject 2, marketing was a huge factor of what I wanted to share with others, there are many ways to market, but some people think the first area to look is a Foreclosure list, this is the worst way to find properties using Subject 2. I never look seriously at any property more than 90 days late on payments.
First of all, someone will need to make up all the past payments and other fees, at that point there may not be any equity at all and you are out of your cash reserves.
Second, the mortgage company (Servicer) may just be done with the loan, too many promises not kept by the home owner, there are more reasons that I go into further in my book and on my website and you can listen to a ton pf podcast by Pace Morby on YouTube.
If I ever give money to a seller for any Equity, I get something in return, maybe it's paying it on a note over time, a lawn mower, car or boat, jetski or whatever I can turn into cash, I limit my cash out of pocket.
As with any Real Estate Investing (or any other business), knowledge is the key, when I decided I wanted to be a Real Estate Investor I knew I needed to get educated, I bought a ton of books (and read them!!!), hired a mentor, paid for classes and joined several REI groups in my area.
Then I took action.
I have seen many people come and go in this business and lose their shirts because they just did this wrong, decided they would rather pay for Starbucks, Netflix, drive expensive cars, go on vacation, watch 5 or 6 hours of TV EVERYDAY, eat out for every meal, sit around with their looser friends and drink beer and more - instead of getting to work, if you treat it as a hobby that is what you get.