Mine are all pretty Z list and from when I was at university so don't go expecting miracles but;
Diva Fever (X Factor 3 years ago (ish) - met them at a club in Leicester, the taller guy was really nice and pretty drunk but the short one was shooting dirty looks everywhere and couldn't wait to get away. This was in the wake of them leaving X Factor, must have been a matter of weeks after, but you'd have thought he would embrace his thirty seconds of fame.
Jamie Afro - again, early casuality of live finals X Factor. He was nice enough.
Chloe Sims (TOWIE) - met her again, in a club recently with her boyfriend who I hear is on TOWIE at the moment. Both were lovely, but Chloe was genuinely hilarious. Was properly friendly and getting into the swing of things laughing and joking.
Booty Luv - performing at a bar I used to work at. They were fun and chatty.
Nick Grimshaw - met him at a service station outside of London. He was really nice, stopped for a chat and a photo and told us he was going to visit his mate "in the country". Genuinely nice.
Sophie Ellis-Bextor - Saw her outside of a TV studio in Surrey, she was so friendly. This was years and years ago, but genuinely, she was so so nice.
Rachel Shenton (played Mitzeee in Hollyoaks) - I always thought she seemed really nice, I saw her in a Morrisons just outside of Stoke and she was reading the celeb mags. I saw someone stop and talk to her and she shot them a dirty look and couldn't even muster a smile at me as I walked past.
Deana (ex Big Brother, series 13?!) - came into a shop I worked in. Was a bit withdrawn, a lot shorter than I imagined but was pleasant.