The most toe curlingly bad piece of live tv has to be the 1989 Brit awards featuring Mick Fleetwood and Sam Fox. If you can find a video online it's worth watching as to how not to present a live awards show. More from Wiki
Sam Fox and Mick Fleetwood (1989)
In 1989, in an attempt to add some excitement and appeal to the proceedings organisers decided to rename the awards to 'The BRIT Awards' presented by Fleetwood Mac's Mick Fleetwood and former page three girl Samantha Fox as co-hosts of the live show. The inexperience of the hosts, an ineffective autocue and poor preparation combined to create a shambolic performance. The hosts continually got their lines mixed up, a pre-recorded message from Michael Jackson was never broadcast and several star guests arrived late.
The Samantha Fox/Mick Fleetwood show proved to be the single most important event in BPI/BRIT Awards history. It was just so disastrous that the British public's interest was revived and the BRITs became associated with risky live TV.