Were they private ads? Those are decent weights and I'd not expect them to be that much lighter (7lb would be great); my Dano Longhorn and Nordstrand shorties are silly light.
Like a few BCers with back/shoulder problems I'm bordering on fanatical about weight for a gigging bass (I own heavy basses that I know I'll not sell but they don't get gigged). I've bought the odd bass or two over the years (cough) and I've been mislead/lied to by possibly 30% - 50% of sellers. I've stressed that bathroom scale hopping is no good, kitchen digital scales are best etc yet basses have still turned up 1/2lb to 2lb heavier than stated. I've threatened to return basses if they aren't what they have claimed to be and that weeded out a lot of chancers. I also completely ignore responses to my questions re. weight that are phrased as "This is the lightest bass I've ever owned/played!", that has no relevance or context and is almost ALWAYS a sales pitch that they can wheedle out of later. There have been a few good folks who weigh basses and confess straight up that they are surprised. I envy those who can get a few times a week with a boat anchor around their neck, saying that my main bass when I started gigging was 11lb iirc... maybe that should be a warning for those who don't have issues yet. LOL