I believe that anyone who can walk can clog, some just pick it up better than others, even if you think you have two left feet, one of the greatest things about clogging is you can fake the movement and still keep dancing (only performance/competition groups are really concerned with perfection).  Catching the beat of a song helps but if you can listen and follow instructions you can do it.  With clogging, you don't need to memorize the order of steps in a dance, a Cuer will call out the steps  just before you are to do it during the dance.  As a clogger, you will have to remember certain steps names, but before dancing a dance, most steps are reviewed.  Plus you have the instructor or other classmates to watch and follow. 

If you have any previous dance experience, clogging will come easy.  (As a former tap dancer, the hardest thing for me was learning the names of the steps: for example a basic is a shuffle step ball change.)  If you have no dance experience, you can still learn.  Clogging is fun and really good exercise, burning as much as 400 calories in a hour.  It doesn't feel like work.

Dances are choreographed from a list of steps (over 150 pages of steps are listed in some reference books).  The level of dance is determined by how difficult the steps are and/or the speed of the dance.  

There are several levels of difficulty: Basic, Basic+, Easy, Easy Intermediate, Intermediate, Intermediate+, Easy Advanced, Advanced and Challenge.

Basic dances usually will include one or more of the following steps:  Basic, Push off, Run, Triple, Toe Heels, Heel Struts

Challenge dances have very complicated sequences that sometimes don't even have names.

Most people are comfortable dancing at an Easy Intermediate Level once they have completed a beginner class.