If by missed we mean didn't see but was seen extremely close to where you were... Ferrari F12 SP America less than a minute from my house (more than once), LaFerrari less than five minutes from my house (more than once). Same case with a grey F12, red F12, Mosler MT900S, Ford GTs, Huracan, other "generic" stuff like Gallardos, 458s, GT3s, etc.
I missed (saw but no shots) an Alvis this summer in the middle of the Adirondacks. It pissed me off because I had my camera around my neck and I could have taken shots, but I didn't see what it was until it was past me.
I don't truly "miss" too many exotics, as in seeing but not getting pictures, and that's because I don't see a lot, lol.

Aventador SV

I've put a couple bad misses in this forum, and I would have put this earlier if I had known about it. So last night, I was checking out a few YouTube videos from the Icons of the Road show to see what I might not have spotted or thought to get shots of, and found a video that really upset me. @dtrockstar1 got a ride in the Mosler MT900S after the show, and they drove it to the OAK BROOK MALL NOT EVEN 15 MINUTES FROM ME!! What makes it worse is that they had it parked there all night, and that I decided against going to OB that night because it looked like it might rain. :(

I doubt I'll ever have a chance like that again...

woah that sucks!!!

Still mad I missed a Ferrari 599VX...

I've missed a 599 SA aperta and a 288 gto in bellevue.

Missed a black Gallardo Sypder today... Probably my worst miss this year.

My worst miss was this red carrera gt.. this is a screenshot off of my dash cam.

Miss by ethan.baker1210, on Flickr

I think I can safely say I have a new worst miss. There was a real Delahaye at a mall 5 minutes from house that my friend texted me about 30 minutes after it left, and the only picture he got was from far away and didn't even have the whole car in it. So not a miss I saw in person, but very painful for it to be so close to me.

About a year ago I missed a 918 Weissach Chassis #663 at my school. I had baseball practice and I get a text from one of my friends telling me there is a 918 in the front parking lot. Was so mad I missed it but ended up seeing it a couple of weeks ago at a show.

My worst miss with me not there is a Ferrari 458 outside the Publix next to my neighborhood. My friend Alex sent me a picture of it just an hour after I had left said Publix.

My worst miss with me there is a Lamborghini Aventador that drove by us for about a mile and a half after both phones in the car (I wasn't driving) had died.

My friend was driving to Vegas today and a lot of the Goldrush rally cars went by him. Tons of Aventadors/Huracans/458's, the LFA, the Bugatti, the 918, and the two Huayras. All he was able to get were phone pics from the other side of the freeway :(

I would've cringed so hard....especially with that BC. Same thing happened when I was on my way to Car Week last year. A silver Huayra with black wing flaps up front past me on the other side of the freeway. Didn't know what had past me until it was too late.