Not such a crazy idea. Certainly no more than owning a zero-turn mower and spending 3-hours every week-or-so mowing it, optimal mowing pattern or not.

I "mow" about 10 acres of pasture with about 25 sheep of the Jacob breed. This is mostly for fun, to feed my family something less environmentally destructive than store-bought beef, to preserve the genetics of a fairly rare breed, and to keep our land clear where we want it clear.

The idea of a lawn mowing service has bounced around my head for the last five years. Through a bit of experimentation on rare days that I've had too much time on my hands, I've found that one can get something pretty close to a machine cut by getting the density of animals such that they graze to the level you want in under about 2 hours. Ideally, the animals should arrive hungry and graze to the desired level before they fill up and sit down to ruminate. If they lay down on ungrazed grass, there will be long patches. The sheep don't stop grazing when the grass gets to the desired level, so one has to be ready to move them when its time. If they are left graze an area to the ground, both the grass and sheep suffer. (Keep in mind that one of the products of a shepherd is market-weight lambs. Hungry lambs aren't growing.)

The catch is that, in order to keep the sheep happy, the lawn has to start just a bit longer than your average property owner would like: Preferably five inches or more.

The droppings aren't a big deal. A swipe with a rake breaks up any piles that drop too close to the patio. With the lawn starting fairly short, the density of droppings shouldn't make for much of a smell.

Using electric-netting fence, one could break an area into bite-size pieces and move the flock several times a day and even a couple of times during the night on bigger jobs. With a bit of experience I think one could target exurban lots and rural acreages to get income from the mowing service and free grazing for the sheep. Can't see a fellow getting rich, but it might make a good retirement gig.