The answer is very carefully, and rarely. If One Dalton's windows look like garbage most of the time, and they have an easy set up for washing windows, I see these silly vanity projects with their needless fenestration (Harvard's science landscraper sings the same tune) as beyond hope of regular squeegee service.
I'm (honestly) confused. At least once a week, usually more, I walk by 1 Dalton and, being a fan, I always check it out -- up close and from further away -- and usually snap a few pix. Aside fromt the glass, itself, being lovely (and probably the most "luxe" aspect of the tower), it's also never appeared anything but exceptionally clean.
What are you seeing that I'm missing? I'm there often, both during the week and weekends, nights and mornings and afternoons, so (again): your assessment is very confusing to me.