I've been trying to determine which laundry pre-treatments work best on which type of stains. My latest trial was a product called Amaze by Sunlight.
For the most part Amaze was great; however, my daughter went to play in the garden on a damp day and got mud all over the bottoms of her pants. I followed the directions on the box, but there were still some mud stains on her pants. To be fair, it would not have mattered which laundry pre-treatment I used. Based on experience, mud is difficult to remove. I'm on my third wash of the pants.
To remove fresh baby spit up stains, Amaze worked well. I found that I could use the soak feature on my washing machine to soak the baby clothes for 15-20 minutes before adding the detergent and the color safe bleach. Again, most of the stains came out; however, the carrot stains were most difficult.
Bottom line, as of this writing I do not believe that there is a laundry pre-treatment product that will remove 100% of stains 100% of the time. Some stains require Mom to put some elbow grease on them.