Shinobu wrote...
Ha ha! I felt like I'd been caught en flagrante! I died more than once, thanks for trying to be nice. BTW, you died several times during that silver match, so I thought you'd be too ashamed to bring it up.
I play bronze too! With equipment! 
Actually, I'm not a fan of the ninja join. Often I'm in lobby inviting specific people -- and if someone else on my FL takes the spot I've just promised to a friend it puts me in an awkward position, because I hate to ask people to leave.
I won't ninja join a game any more than I'd enter someone's house without knocking.
I was a GI with 700 shields, what's your excuse?

Also, if I ninja join into a lobby with three other players, I'll ask if I have taken a spot that was meant for someone else and will f*ck off without protest if I'm told that I did.
I have had other players ninja join two of my gold solo attempts and one plat solo attempt. Not going invisible is just asking for it, since anyone on your FL can just hop right in after opening a chat window.
Personally I like it when friends ninja join my games (not the solos, but that's what invisibility is for). If they asked me beforehand, I would only notice it sometimes after the match. I never check the origin pop-ups during games. If we're in a match and one or two guys short and then backup arrives ... that's kinda cool. So if you see the orange button in my chat window, feel free to hop in.
I ninja joined bauzabauza's silver game yesterday, shot some stuff and then started meleeing him. He melee'd back. We proceeded to kick ass. much more fun than PuGs imo.