I have done about 4 regular mortgages for purchase and 5 re-fi's. My situation is complicated because I have 3 rentals. My advice to you is to not believe anything a loan officer says and read all of the paperwork.
When I bought my first house, I got a pre-qualification letter for a loan at 7%, but the market rate was 6%. After I got a house under contract, the mortgage broker was trying to tell me that I should sign with them at 7% because they provide better service. I had another broker try to talk me into a no-document loan at a 0.75% higher interest rate. There was no reason for a no-doc loan other than a higher commission for him. I was young with no previous experience in real estate. They could see it. They were like sharks with blood in the water. However, they didn't know that I am the type of person that does their due diligence.
When I bought my second house, a loan officer at the credit union took a very strong position that I didn't qualify because my debt to income was too high because I owned a rental. After some investigation by myself, she assumed that I did not report my rental income on my taxes. When I showed her my taxes she was surprised that I claimed rental income. "I guess you do qualify"
When I bought my 3rd home, I had a mortgage broker take a very strong position that I didn't qualify for traditional financing, so I needed to do an investment loan at 0.75% higher interest rate. He spoke for about a solid 20 minutes and wouldn't let me speak. At the end, I said that I have a pre-qualification letter from another lender that says that I do qualify for traditional financing. It was really awkward because at that point he realized that I knew my stuff and it was a waste of time to continue to spit bullshit.
When I bought my 4th home, I caught one broker doing a bait and switch. We both signed a good faith estimate with a rate lock. About 3 days later, he called me on the phone (which he never did) and said that he found me a better deal and will save me $1200. He then asked for my permission to cancel the original deal and draft up the new deal. I agreed over the phone without seeing the new deal. However, when I got the new deal, the rate was the same, but fees were higher. I asked him why the fees changed and how the new deal is $1200 cheaper. This is what he said, "The fees didn't change, but some of them were missing. I am not responsible for the original estimate because it was auto-populated by the program." He then proceeded to say something along the lines of, "If I am not willing to trust him, it's not going to work and I should shop for a mortgage with someone else." He never answered the question regarding how the new deal was $1200 cheaper, because it wasn't. It was actually $600 more expensive that went directly into his pocket. I was asking for a logical explanation. He wanted blind trust so he could take advantage of people. Once he realized he wouldn't be able to scam me, he cut ties with me and went looking for someone else.
Good luck.