If it's a movie/production place and they labelled it cloth tape, then it's probably not gaffer. Cloth tape has less stickiness (that is, it sticks less to things) and durability.

Even though it's likely not the same as anything you get in the States, this is what I normally buy:
http://www.officeworks.com.au/retail/products/office-supplies/packaging-and-mail-room/packaging-tapes/specialty-tapes/st3145bk?cmpdt=20100826&cmpcr=preshop&cmptp=PPC&cmpprv=lasoo&cmpprd=st3145bk&cmplnk=

(Wow, I just discovered that they sell it at Officeworks in Aus for less than half of what I've been paying at my very distant lighting equipment hire company. Yay!)

I always thought that gaffers tape was cloth Daryl. Cheap duct tape is normally kind of a loose weave that is embedded with plastic.

Seems that I read Duct tape is vinyl cloth coated  tape while gaffers tape is rubberized cloth coated.

I think you may have hit in the head Billy.  I know that in duct tape you can see the weave of the fabric in it very easy. It is very open, where as gaffers is more like if it was cotton fabric.  The other way I can tell is that duct tape is normally shiny and gaffers has a matte finish.

BTW, do you all know what a Gaffer is? http://en.wikipedia.org/wiki/Gaffer_%28filmmaking%29

BTW, do you all know what a Gaffer is? http://en.wikipedia.org/wiki/Gaffer_%28filmmaking%29

That makes sense ! Gaffers tape

Yes, I'd agree that gaffa is generally more of a tougher cotton weave (thicker strands). Most people need to use scissors to cut gaffa off a roll, whereas cloth you can tear with your hands. If you have two rolls - one of each - you can easily tell the difference from the weave.

Personally I prefer Gaffers to Duct tape, as duct tape disintegrates sooner.

This is what I found out about Gaffer tape and Cloth tape.

http://en.wikipedia.org/wiki/Gaffer_tape

http://www.wisegeek.com/what-is-cloth-tape.htm

Ok after much debate and looking at so many stores and prices that went from OK to Ridiculous.  I found the tape that actually says gaffers tape right on it and it was made by a reputable company, 3M.  It is about 2" wide and I will say comparing the two it is like night and day the cloth only tape had a week stick to it as well very flimsy it was about $17.00 CAN a roll for 60 yards.  I got the same about that is actually REAL gaffers tape and it cost me $35.00 CAN per roll with 60 yards as well.  I had completely ran out and had nothing on hand that I could compare.  I found the stuff at a artist store that sells painting supplies, canvases and frames.  I guess they use it to attach canvases to the wood frames. 

Words of advice......
I need to say to watch out!  One of the places that I went to was selling the same brand and company same amount that I purchased at a movie/theatre supply shop for $17.00 CAN they had exactly the same stuff no difference same company everything and they were selling if for $53.00 CAN. So please look around and make sure it says it is gaffer tape and NOT cloth tape.....however I will say that 3M that I bought titles it Gaffers Cloth Tape....but it still has gaffer in the name.

Happy searching....

Daryl H