Note: this is from a guy who sells tables, i'll try to keep the subliminal commercials to a minimum :).
Note2: if foosball to you is just a spinning toy or game,then you won't want to buy from me and/or pay more than $300for a table, BUT, please read on, there are some importantthings to consider when shopping for any foosball table.

SPINNING

• Not an issue if you are buying a toy/game for the kids.  Shop around the low end.. of course if money is no object,  and you want a really sharp looking table... call me :)
• If you want to develop the "skill" of the game/sport then  you will want to look for a table that has a consistent  roll or surface, a table that has a "round" ball that  rolls round, a man/ball/surface combination that lets you  stop, pin and maneuver the ball.  You need to shop the   $400 and up range.

AGE OF FOOSERS

• For the kids only.  See spinning above, but note that there  are 17 years of age and under events on the pro tour, and  there are kids in their early teens and younger that compete  in the open events - AND WIN!
• For the adults and kids, a table with adjustable height can  be a big plus... the pro tables are set at 36" in height.  A  bit high for very short foosers.  Several models in the pro  line of tables can be adjusted a few inches.
• Adults or Big Kids, College "kids", or lots of kids. You will  definitely need to look for a high quality cabinet.  There are  tables that will stand up very well to high volume/abusive   play, Yes, even in your college fraternity or sorority :)

ROOM LOCATION

• Physical dimensions of the full size foosball table.  Length 56", Width 30"
• Don't for get the rods stick out, and players need room.  Minimum suggested playing area - 7 foot by 8 foot is good.  That'll give you a little over 1' at each end of the table  and almost 3' on the sides for players to stand.  For big  kids a little more room would be recommended.
• Appearance of table - There are high end furniture grade  tables that look sharp.  You can even order custom finishes  of the table to match your decor.

QUALITY OF CABINET

• Look at how sturdy the table is.
• Look at the surface, is it flat?  can it be leveled?  Check  one piece surfaces with ramps in the corners.  Some make for  rather large "dead spots" in the table where no playing   figure can reach the ball.  Others have weird rolls.
• Look at how the side walls of the table are held together.  Rough play will cause a lot of banging of the side walls and  if the sidewalls are not held together in the middle of the  cabinet you could have them separate.  Most low end tables  have "tie rods"  that hold the sides of the tables together.  Usually just "3" one in the center, and 2 on the ends.  Higher  end tables will have "L" shaped bracket that run the length  of the sidewall that secure the sidewall to the often times  much thicker surface.
• Width of the sidewall.  Wider is typically better.
• Thickness of the suface.  Thicker is typically better.  (note: on thickness - the old style "TS" tables had a  somewhat flexible surface that was key to it's man/ball/  surface feel.   this is no longer desirable since the "ts"  clones typically come with very poor quality balls. With  newly designe tables the new man design and ball compounds  allow for a excellent man/ball/suface feel, a consistent  roll AND a more durable thicker surface.)

RESALE VALUE

• Put it in the laundry room, you can easily dry 16 items of  clothing at a time by neatly hanging them on the rods :)
• Turn it into a kitchen/work/play table - put a table top  on it and bar stools around it for a nice card table J
• Take the legs off and use it as a coffee table... or my  favorite... Remove the rods and you've got a dice table :)
• Sell It!  Consider the potetial market in your area and  you won't feel to bad if you can easily sell it for a  hundred or two less than what you paid for it.  Regardless  of what table you buy, you can usually sell it in the local  paper for 1-3 hundred less that what you paid for it.

SUGGESTIONS from Jim Waterman...

• Don't pay too much... shop around!
• If you appreciate foosball as a skilled game, then consider  the Tornado line of tables.   The entry level table has the  important man/ball/surface combination that will allow young  players to learn ball control and skilled shots.  (Note: this  table "The Whirlwind" can be had for under $500)
• If Money is a big factor, you can always buy low, and then  upgrade at a later time if you and your family become total  foosball fanatics.
• Don't pay too much for a middle of the road table that will  not let you learn the skilled style of play.  If you want  to sell a midrange table, your resale market is smaller.
• If you are destined to spin... save yourself some money and  shop local for tables under 3-400.