I have one particular customer who always has a lot of dog spots in her lawn, to the point that she has me reseed her back lawn every fall because it has thinned so badly.
Last fall, I started using 1-2-3 Compost Tea from ICT Organics on my customers' lawns. The idea popped into my head one day that if the microbes in the ICT compost tea break down nitrogen that they might help with dog spots, so I mixed up a batch in my 2 gallon pump sprayer, I don't remember the exact amount of product, but I do remember that i mixed it as if I were going to spray 6,000 sq. ft. with the batch. I then sprayed the dog spotted areas very heavily (roughly 3/4 - 1 cup of mixed product per dog spot) with the product. By the next week they were green again. After that, I just kept a batch of it mixed up all the time and I sprayed all dog spots on all of my customers' lawns every week after mowing, and the results remained consistent. I calculated my cost to be around 12 - 15 cents per dog spot, or about $4.50 per sprayer full, which may be a little more expensive than reseeding it, and of course I am going to lose the income from reseeding the one lawn every fall, but it kept the lawns looking better. This year, I am going to mix it in a spray bottle and carry the bottle on the mower with me to save time.