The two worst ones I ever saw (and I am sure they must have both been mentioned already) were Ruiz-Oquendo (total snoozefest) and Wlad-Ibragimov (which I had the misfortune of seeing live). I'm sure there others, but those two were terrible.
Douglas-Holyfield? :huh I've seen many worse than that. At least Holy ended that one on a beautifully times shot early in the fight, inherently making it more exciting than many other heavyweight "title" fights.
Yes, that was horrible. Luckily, it was followed by Golota-Byrd, which was actually one of the more entertaining contests in recent heavyweight memory.
gomez-vitali....i usually stay and watch a fight all the way through, in like the 5th round i had to get up and take a **** in the middle of the round...i never do that.
Briggs - Liakhovich was awful (except the knockout). There were often times where nobody would throw any punch for 30 or 40 seconds. In most rounds Briggs threw about 15 punches max. Liakhovich was trying to imitate Briggs and got very lazy as well. Steve Holdsworth's and Bob Mee's comments on Eurosport were pure comedy: "People actually paid good money for this fight..." Then they would just drift off and talk about something completely different. If there had been no knockout this would have been the worst title fight ever: one guy too anxious of the other guy's power, the other guy too asthmatic to throw any punches.
Wlad vs Sultan - it was a shocking display, made worse because Wlad clearly could have taken him out any round he really tried, made worse because of the batting-hand technique Wlad used for 12 straight rounds, made worse because it was the first heavyweight unification in forever.