I've tried my fair share of mascaras (I'll always buy a different brand, I rarely ever buy the same product more than once, except for L'oreal Voluminous Mascara) and I've come across a few that I was really, really disappointed with. I almost always do my research, and will read reviews on any makeup product that I'm thinking of buying (try http://www.makeupalley.com) and all of these products got some great reviews. And yet, I was still disappointed. How frustrating. Here's my list of mascaras that really, really suck.
DiorShow Mascara - Ugh this stupid mascara was getting amazing reviews so (obviously) I HAD to try it. I was very disappointed, the mascara brush was WAY too big for my eyelashes (similar to Benefit's Bad Gal mascara brush) which was super awkward to use, especially on the lashes that are close to the inner corner of my eye. I also found that the formula was really dry and didn't apply much product to my lashes. Don't bother with this dumb mascara, it is way too overpriced, I would only ever recommend you buy it if you've already tried a friend's or something and you love it.
Smashbox Bionic Mascara - I bought this a couple years ago as a Secret Santa gift, but ended up keeping it instead because I couldn't resist try it out haha. It's an okay mascara but it's water resistant and if you get any little mascara smudges on your eyelid, it is SO difficult to get off and you end up ruining your makeup because you have to use a makeup remover for it. Once the formula dries out, the brush gets super gross and is impossible to use. My mom insisted on buying this product for herself because she had read such great reviews on it (even though I TOLD her not to) and ended up disliking it just as much as me. So HAH I was right. Listen to me.
CoverGirl Lash Blast Mascara - I think you have to have a certain type of eyelashes to like this product. My eyelashes aren't very thick and are kind of short and I found that this product didn't really do much for them at ALL. However, my mom really likes this product and I think it's because her lashes are thicker and longer than mine. If you've been blessed with naturally gorgeous eyelashes then this mascara could work for you, but I recommend you trying it out before buying it.
MAC Pro Lash - This is the first and only mascara that I've tried of MAC's and it really did suck. I got suckered into buying it because I had leftover money on a giftcard and it was one of their cheaper products, but I really wish I hadn't. It's their first mascara they ever released and the formula wasn't thick enough for my lashes and just added colour to them instead of body and volume. It also has a really funny smell, which isn't fun (it had a weird smell when I first bought it too, I think MAC mascaras are infamous for their weird smells). However, I use this mascara on my bottom lashes because I like the brush and it does an okay job. Buy one of their other mascaras though, I've heard that MAC's Plush Lash is great.