You're totally right, it can be a dirty word but most of the time it's just like negative. Like little children, when they're arguing, would say to each other (or their parents LOL) "You suck!" It basically means I don't like you right now. Or like when something bad suddenly happen, like you got a flat tire or something, you would say "Well this sucks..". Also in a newer slang version, Americans tend to use also "blows" instead od "sucks" (you can guess why) in the same situations, but I sincerelly don't recommmend it. People are not gonna get the joke :)

Maria,

Even though this is the year 2013, I believe that young ladies should  not use that word -- ever!

If a young lady uses that word, some people (not just old people like me) will lose a little respect for her.

If you interview for a job, and you use that word, I am sure that many managers would  think less of you.

In other words, do NOT use that word -- even though many young people think that it is "cool" to do so.

The word "suck" actually means to put something in your mouth and try to swallow as an infant/baby "sucks" a nipple on a bottle of milk. A calf will "suck" the cow's udder for milk. A child will "suck" on a candy or lollypop/lolly/"suck"er.

This word also has a sexual overtone that would not be appropriate to discuss on a public forum, so yes, it can ba a "dirty" word. I don't let my young children use this phrase.

It's not proper English, but I also use the term if something bad or inconvient happens to me.

Example- If I drop an egg on the floor and it smashes and makes a mess, I might say a swear word or "Well, that "sucks"!

I believe that this term actually comes from a person or animal that "sucks" a raw egg through a hole. SO, the saying "You suck!" or "You suck raw eggs!" would be consider a derogatory or negative statement about that person.

Some people (as evidenced above), will take offense at it when used in a certain way. Personally, (in my experience, anyway), it seems to have fallen out of usage for seven years or so. Here are two examples of the word used according to its original meaning: "I have read that some have stated it is effective to suck a poisonous snake's venom from a wound, but I think this is possibly a dangerous practice, especially if done incorrectly or by an inexperience person."  "Most dentists have a small vacuum to suck excess saliva from a patient's mouth."

I agree with what others have said. Using the phrase "this sucks" to express your displeasure is not the worst thing you could say, but it still has vulgar connotations, and I personally try not to use it.