pcgrandma : I'm sure Vinagar will kill weeds in the lawn . There will also be considerable die-back around the area of treatment . With boiling water , ( if you were considering it ) after the weed died you could remove damaged ( dead ) weed & grass , and easily reseed the area and have grass growing in a few weeks . With Vinigar I would find it highly unlikley that much would grow in that soil but other weeds if anything . The vinigar will drasticly change the PH of the soil making it an unlikely place for healthy grass to grow .
I think digging out dandilions is the best way to get rid of them in the gardens . I use a big shovel and remove as much dirt as possible so as to not disturb the roots . Set aside dirt & roots on plastic or in a bucket or cart . Replace soil with composted soil . The dandilions and soil are taken to the compost pile where the soil is knocked off as much as possible onto a 1 inch wire mesh sifting box . The dirt goes into the compost and the remainder of the plant is dried and eventualy burnt . If you think you didn't get all the roots in the hole , then you could pour boiling water into the hole and when water has drained add fresh soil .
There are good products that kill near all weeds without killing the grass . They are not cheep and I dought if they are safe for the environment . If you have the time to be frugal , then digging and reseeding is the way to go . To keep the birds away from reseeded areas , you can nail a small peice of burlap or apply a light layer of hay , over the area .