I am a mortgage broker so the first thing I can honestly tell you is that most of the crooked ones have been weeded out (or more aptly regulated out). There are so many restriction on how we make our money in the mortgage industry now and what fees can be charged that there is very little room for "ripping clients faces off". Having said that you have to realize that there are basically 4 categories of lenders.
Banks - Likely should be your last choice, they typically have the highest rates and the least experience with difficult loans.
Small mortgage broker shops - a single man or small team will have rates just slightly better than the banks (so they are usually a better option) and will likely have access to multiple wholesale lenders and a lot more experience so can place and structure much harder loans. If you are self employed, have challenged credit or are dealing with a wonky property then this is probably where you want to start.
Credit unions - are like banks in that you less likely to get great experienced loan officers and are going to be more restricted on what you can get done, but because of the tax advantages credit unions enjoy their rates are among the most competitive. Credit union rates however can vary wildly over time and may not always move with the rest of the market, in other words they'll be tied with banks sometime and beat everyone by a half a point in rate some times. I've seen pentagon federal credit union have some screaming deals occasionally, and yes everyone can get access to them not just government employees.
Deep discount cube farm online lenders - REALLY hit or miss, your customer service is going to likely suffer and god help you if there is anything the least bit hard about your loan but if you have low DTI high credit and are in general doing a vanilla loan then they will likely have the best rates bar none.
Lastly yes everyone needs to get a couple of fee estimates from a couple of different lenders and lay them down side by side and compare them. Going in to how to read a GFE is beyond the scope of a forum post, but I will tell you if there is anything even remotely complicated about your loan please don't make your choice only on price. Remember you get what you pay for. Interview them, spend 20 minutes over the phone with each of them or even an hour in their office, make sure they are knowledgeable enough to ask detailed questions about your financial situation, trust worthy enough to provide you a good education about the process and that they are looking forward to try and address potential roadblocks to your loan process ahead of time.