Grant was also a drunk.
When Lincoln was told about the problem, Lincoln said, I can't spare him, he fights'.
Grant was a great general.
Abraham Lincoln
Grant may have gotten drunk a time or two but his bosses/Generals over him were far greater liars and back stabbers then Grant ever was a drunk. Most of the rumors about grant being a drunk were lies. Eventually those back stabbing political Generals over Grant were fired or knock down the ladder a few rings.
That's a tricky question, but Grant didn't have a typical alcoholic pattern. He never drank when anything was going on. No drinking in inappropriate times and places. No drinking under pressure. It was a hard-drinking age, and the stories of Grant's drinking presumably had some basis in fact, but the stories were also all rumor and innuendo, mostly hearsay and mainly spread by people who had personal scores to settle. Grant continued to drink socially throughout his life after the war without any significant incident; he authored a minor literary classic, a model of clarity and precision, as he was dying of cancer; and he had an exemplary marriage and family life. This is not the pattern of a typical drunk.
One of the historians -- I think it may have been Shelby Foote -- concluded that Grant probably got drunk easily and had some accidents along the way, but that he was not a drunk. His Old Army reputation for drinking was based on his period in the Northwest, where by all accounts he terribly missed his wife, fell into what we would today probably diagnose as depression, and self-medicated. The Army was a small, ingrown, and gossipy place, and Grant never outran whatever happened at that time. But that is not the same thing as being alcoholic, which today we undertand as an addiction and view as being chronic and progressive.
Bottom line, if Grant was an alcoholic as we understand the term today, he spent the last 40 years of his life as the greatest dry drunk in U.S. history. But his personal demeanor, family life, and professional bearing don't look like a dry drunk. So I tend to agree with the "sloppy drinker but not a drunk" theory.
P.S. The definitional issue is important here. Most people in the U.S. today drink and are not drunks -- despite the fact that the vast majority of people who drink have an occasional drinking-to-excess episode on their records. If it's with your buddies on a fishing trip and no one falls into the lake and drowns, nothing comes of it. If you kill someone on the highway or humiliate your wife in public or disgrace yourself in front of your boss, it gets more serious. But such an event, however painful, does not necessarily mean you are a drunk. The pattern is the key.