I'll bluntly state, I typically check everyone's logs who join a farm party I've involved with for no other reason than to gauge my expectations. The less experience, the less likely I'll stay beyond a handful of attempts because I just don't believe enough players have the skill to clear. When I plan to farm something like Shinryu EX, I'm looking for fast and efficient runs, not multiple wipes to silly mistakes. Why? Because unless I get lucky, I'll be doing this for a minimum of 99 times. Now exceptions can be made. If the group has a good atmosphere and makes the attempts humorous, I may stick around longer even if it's less productive. I don't simply look at FFlogs, see a bunch of green and grey and immediately think you're trash. I just like knowing what I'm getting into, especially if I'm on tank or healer. A weaker co-tank means I may have to adjust my playstyle. Likewise, on healer, I am very aggressive and like having a general idea of what my co-healer can handle. If they have grey parses, I'm going to be far more DPS oriented to make up for their lack of damage. On the other hand, if their HPS is equally low, or they tend to DPS only, I know to put myself in the "healer" role.
Basically, FFlogs gives me a buffer instead of adjusting while completely blind. If you hide your logs, sorry, but I will assume you have something to hide. That may not be the case, however many people I've come across do so to hide poor performance.
Like Hoodrat mentioned, FFlogs provides that context if you know how to use it properly. I can deduce exactly how you died, what killed you and why. Right up to if it was someone else's mistake that snowballed.