Even though some of the places you may go are one star, the experience gets a five star review; let me explain why.
Glasgow is more than just the fancy restaurants that serve foods from round the world, and style bars that serve fancy cocktails. There's a whole other side to this wonderous city, and while it's not something that might grab your attention, or make you sit up and say "YEAH!" it is something you have to experience.
As for the Subcrawl, it takes in one of the best things about Glasgow, in my opinion - the underground. It's clean, it's fast, and it's regular. Get yourself a free smartcard online, and you can travel all day for under three quid! You can also register and get discount vouchers to use at local businesses - always a good thing!
In any case - the fabled Subcrawl. The rules vary from person to person (you can split into teams, you're not allowed to sit down on the trains, you have to have a different drink, you have to go certain ways... all negotiable!) but the the basic concept is always this: A drink at the nearest pub to every Underground stop. That's it.
Some stops are problematic - I believe the bar at Ibrox only opens on matchdays, and Shields Road is a long walk for the uninitiated or inebriated. Allowing for this, you simply have two drinks in different pubs at other stops. It might technically be cheating, but the principle of seeing more of Glasgow is still the same.
Some advice from a semi experience subcrawler AND pub drinker (*hic*) is to start in the city centre, at St Enoch or Buchanan Street - head south on the Outer Circle, thus hitting the Southside and the... shall we be generous and say... less salubrious haunts on the tour.
There are some hidden gems south of the river - the Laurieston is a prime example, one of the finest pubs in Glasgow for my money - to balance out the other places. By the time you reach The People's Republic of Govan, you'll have seen the other side of Glasgow and be ready for the stylishness of the West End-to-City Centre crawl.
The best thing about the Subcrawl though, is the people. The people you see in the pubs you don't usually visit, the people you see on the Subway but more importantly, the people you do it with.
I'd only briefly met one person on the Yelp Subcrawl recently organised by Austen - yet by the end of it, I felt I'd made a whole ton of new friends. Simply by chatting and having a right good laugh - I don't think I've ever had a day where I've laughed as much in a long, long time - and that for me, is the essence of both the Subcrawl and Glasgow.
So, I would sum this up as one the essential things to do for anyone who has time to kill in Glasgow. It's definitely a Summer thing, as the extended hours of daylight and warm (ha!) weather are a must. Eat before you start, eat somewhere along the journey, and take your time. Most importantly - enjoy yourself and your surroundings.
And don't run up the down escalator at Kelvinbridge. It's not big, it's not clever, and you WILL look stupid. I speak from personal experience!
I put together a list with some pub suggestions here: http://www.yelp.co.uk/list/the-glasgow-subcrawl-glasgow read more