I've been tying myself in knots trying to give a brief and succinct response to this, because I've spent a lot of my life worrying about whether I should profess likings for things that my peers deem to be shit, but ultimately: no, don't feel ashamed. Thing is, if your tastes generally fall outside the mainstream, there's always some dissonance when you find yourself enjoying something that falls within it.
Many of my teenage friendships were built on a shared love of music, be that comparing notes from the previous night's Peel show or swapping Dreamscape tape packs, or whatever. Back then, we thought we had better taste than the kids buying Now! compilations or taping the Top 40, and to some extent the "I like good music, I'm cool" thing was a badge of honour and a way of differentiating ourselves from people we though were twats. I began to define my music taste as much by what I didn't like as what I did, developing some sort of superiority complex - "oh god, you like that shit?" - and this was reinforced by friends with whom I obsessed over what I did like.
I think this continues into adulthood, but in addition to friends, you discover internet forums to share your love of (what you consider to be) cool music, and to sneer at those who don't 'get' it. So when you find yourself at odds with your friends/forumites, liking something 'uncool' that the 'twats' you try so hard to differentiate yourself from also like, there is doubt and (my point at last hoves into view...) shame.
This was my problem. I thought: I can't like song X/genre X, the people whose music taste I respect don't like it, they'll think less of me. And the people who I think are idiots do like it, and I don't want to associate myself with them in any way. I am ashamed to like this.
I spent much of my teens and early twenties grappling with this (and in fact in reverse as well - "Ugh, hipsters like that, I'm not a hipster, my taste is more real, bloody hipsters,"); I cultivated my snobbishness by working in a record shop for 6 years and generally acting the cunt to perfectly nice customers who wanted to buy things I thought were shit (Oasis, usually); and effectively talked myself out of liking things that I now think are great because I was worried what other people thought. These days? Fuck it, if I like it, I like it. I don't care what my friends or peers think of the song, or who else likes it.
/rant
On the pop/trance tip, I'm fond of that Chris Brown record you posted, rivetrenuck: the synths are great, the vocal melody is catchy. I don't like the Guetta/Rihanna one because of the auto-tune fuckery-foo,and the other two were ok. There is stuff in this style that is genuinely obnoxious - that Black Eyed Peas one that interpolates Dirty Dancing (and actually, almost any Black Eyed Peas) - but the odd track here and there is quite enjoyable. This style absolutely dominates mainstream radio and clubs, and it's on in the background at gyms, shops, etc. Inevitably you're going to hear a lot of it and end up finding one or two that stand out. Give trance a chance, innit.