In the context of Starcraft (and it is different in other games), smurfing referred to utilizing an account with a lower ranking (usually ICCUP) than is accurate for you as a player, to beat up on lesser players.
Since Starcraft 2 has a built in ELO style system, this would mean buying a new account (or destroying your own ranking) and losing all your matches to be placed in a league below your skill level (or using one that is already in such a position).
Since ELO style ranking systems require a sample size of multiple games to make accurate prediction of the skill level, players can trick the system into believing they possess a lower skill level.
Smurfing is not unique to ELO style rankings either. Many tournaments are held for lower skilled players and by misrepresening themselves, highly skilled players can enter these tournaments. This often times constitutes fraud or cheating, but may be by design. For example, the Team Liquid Attack pits a professional player against a series of lesser players. Often times they will intentionally mix in another professional player and present him as a lesser player for comedic value. This is by design (and fun to watch).
Usually, however, smurfing is tantamount to taking candy from a baby.
I think there's a difference between the dry definition of a port and the thing that people complain about.
The term "a port of a game" means a game was developed for one set of platforms, and it was later released for other platforms. Technically, a game released for multiple platforms from the get-go - such as Crysis 2 you have mentioned - shouldn't be called a port.
But that's not what people complain about. A game can be a port from its version on another platform, and still be a great game which was carefully ported. What people really complain about are games that exhibit elements not appropriate for the platform they are running on; unfortunately, this is a common occurrence with ports, hence the connection.
The problem isn't really exclusive to ports - a port may be a good port (modified to fit the new platform perfectly), while a non-ported game released on many platforms may simply work better on one platform vs another. The truth is, though, that many game today are designed with consoles in mind, and unfortunately their PC version (whether a port or a simultaneously-released version) is inferior because they are not properly adapted.
Common examples of things not properly adapted are UI elements - e.g. where mouse navigation is lacking while keyboard navigation is fine; aiming - where in consoles FPS often have auto-aiming mechanisms that should not appear on the PC; driving - where the accurate gamepad control does not have a parallel in a PC keyboard; etc. One of the biggest ones is something a little less obvious, and that's performance - a poor "port" might have poor performance on the platforms it was not originally designed to work with.
EDIT I've recently found this nice piece listing problems or missing features that plague PC releases of console-oriented games nowadays. Although it specifically bashes some select titles, it does mention problems that I've seen in many recent games, and I thought it's worthy to include the link here.
Best Answer
S as a ranking above A originates from Japanese games. Aside from Metal Gear Solid 4, it has also been used in other games, such as Gran Turismo series (driving licenses), Devil May Cry (level performance), Final Fantasy VII (chocobo classes), Guilty Gear (character rankings), and countless others.
While the origin is universally acknowledged as Japanese, apparently, no one really knows what it actually stands for. It's been speculated that it stands for anything from Super to Special, but there's no confirmation that I can find of any sort of "official" meaning.
Giant Bomb's S-rank article states that because C was the lowest passing grade in the Japanese school system, "S" was used to allow for a wider range of grades. See the following excerpt:
The Rank Inflation article on TVTropes mentions the S-ranking as well, however, without any speculation on the origin:
Urban Dictionary's S-Rank article (linked article is SFW, but the site itself can have some very NSFW content) also lacks a concrete origin:
In addition, all 3 of these sites are editable by anyone on in the Internet, so I'm not sure that any of these can be considered concretely reliable, and the assertion on the Giant Bomb article that it's related to the Japanese grading system has no source and isn't one I can confirm because I am not familiar with the system.
Basically, as the TVTropes article stated, it's just a way for there to be a ranking that is better than the "best", similar to how some games have Platinum medals on top of Gold.