Wait a Minute! is that a blues trio playing a HENDRIX song?
John Mayer Trio's falsettos in that song > Jimi Hendrix Experience's falsettos in that song. Plus, I much prefer that bass playing and tone. I was never a huge Noel Redding fan.
Anyways, I've really enjoyed this thread and agree with most of it, particuarly on the subject of live tuning during a set, bands with no stage presence complaining about the crowd not reacting, and rock bands using music stands.

Anyways, for my Top Five...
1. Bands that list in their bios a bunch of C-list national bands they've shared the stage with as a way of upping credibility. What it generally means is "We sold tickets for some promoter to open for some band who didn't have enough clout to bring in enough fans of their own."
2. Bad tone. The scooped guitar tone and ultra low-end bass tone may sound bad ass in your bed room, but it sounds like undefined mud in a live situation.
3. Bands that cover songs that require more instrumentation than the band has. I understand that it's possible to cover tunes that originally employ two guitars when you only have one guitar player through rearrangement, the bass taking on a more up front role, effects, looping, thick FOH mix, etc. However, trying to cover Bat Country with one guitar and no Eventide harmonizer is just going to sound lame. The same goes for covering material and missing out on important vocal harmonies. If you don't have an awesome falsetto singer, it may not be a good idea to try and play I Get Around by the Beach Boys and axe Brian Wilson's vocal because "it's not that important."
4. Purposefully misspelled band names. Sometimes it's clever. More often than not, it's lame. It's even more lame to take a perfectly fine band name, and replace any ending Ss with Zs. Can you imagine if we had The Eaglez, The Rolling Stonez, and The Outlawz? Maybe Miles Davis should have changed his name to Milez Daviz.
5. Bands who openly comment over the mic about the lack of a crowd on a sparse night. It's unprofessional and just makes the night drag on longer, IMO.
On the topic of dress, since that's of a debate in this thread - A band shoud look presentable. Whether you like it or not, how you look on stage is important. That doesn't mean you need to wear matching suits and ties on stage. However, people are paying to see you PERFORM. Otherwise, you might as well just perform behind a wall at your gig. And even Pink Floyd made that an artistic experience when they did that. As far as shorts on stage - It can be cool and acceptable or very lame and dorky depending on the situation. I'm not a big shorts fan to being with. I do have a cool pair of Rude Boy styled pin-stripped shorts that are very cool and work well on stage and the style of music I currently perform (i.e., modern rock from Green Day to Disturbed and some 80s). However, I wouldn't dress like a frat boy and play Pantera. It's all about the situation.