Pilot Preras: A mystery on my part

I generally hear good things about the Pilot Prera fountain pens but my experience with them has been mixed. Some of Preras I've tried have been incredibly smooth while others were fussy hard starters who bitched more than me on Student Loan Bill due-day. And it's always the "vivid pink" Prera that was problematic. Whether in a medium or a fine nib, I often had problems with skipping and hard-starting. Then I'd give the pen to someone else and they'd rave about it. So clearly it's just me. But so far, the two Preras I have (pink with a medium nib; soft blue with a medium nib), have been behaving. But I'd love to know what it is about the "vivid pink" Preras (only pen companies outdo cosmetic companies in terms of marketing) that they wouldn't work when other color Preras do. Maybe it's a bias against pink pens. But what I like about the Prera is that it's a small, well-made, sturdy pen that is still comfortable to hold and write with. The cap snaps shut with a satisfying "snap." I can throw it in a bag and not worry about it getting broken. It takes Pilot cartridges and two kinds of Pilot converters for bottled ink.
And it comes in pink :-)
(although I actually prefer the light blue one. Whatever. I'm a sucker for pastel colors in general).