Can you survive AND positively contribute to a successful outcome in a timely matter? If you aren't completely confident, think twice. It's totally ok to tell the LFM host that you don't know the content well or ask what you need to bring. But if you're not a good fit for the party, there's no need (nor is it constructive) to harass the party leader. Unfit could mean a lot of things, including but not limited to: not enough HP, not self-sufficient enough, not knowledgeable enough, insufficient gear/pots, not the right build for the situation, taking too long to get to the quest (being the last to join the party and spending 10+ minutes in the crafting hall asking crafting questions in party chat while the rest of the raid party is waiting inside the raid for example), etc. If you're really interested in exploring the endgame, then be more fit.
EE raids and quests are no place to pike. Some HE raids also fall into this category: Elite Abbot and Elite ToD come to mind.
We all play to have fun. If I host an LFM, I will try my best not to waste your time, and I do expect reciprocation.
Honestly, I used to screen (via myddo and "do you have DR-breakers?") more for Shroud in the early days of the server than I do now for EE raids and quests. Typically I'll just take the first X number of PuGs that apply, but I do have the expectation that applicants have some clue about the content and requirements if the posted LFM is for EE.
The current design of the game makes Casual to EH a snoozefest, and EE challenging for the best geared parties. There's almost an order of magnitude difference. It's a challenge. Challenge is fun. Dealing with lag is frustrating. Dealing with clearly unprepared willful pikers is frustrating. Frustrating is not fun.
Like all PSAs on the forums, I'm sure this won't reach the eyes of the intended audience. But I felt like saying something anyway.