I believe only solid colors are cotton broadcloth. Broadcloth refers to a type of manufacturing process. Most of the quilting cottons we use (including muslin) are not broadcloth. I've often wondered why solid colors are always broadcloth. I'm thinking the manufacturing process may promote colorfastness of solid colors. Not sure, though.
http://en.wikipedia.org/wiki/Broadcloth

Quality quilting fabric is usually 60 - 65 thread count.

Thanks for the information. I think we all have faced this problem.

Came across this today,
"Average cotton cloth has a thread count of 60 x 60 threads to the inch, sometimes called 60 square. It may be thin or stiff and it shrinks a lot in the wash. Expect your batting to migrate or beard through these widely spaced fibers over time. Better fabric - which is what you usually find in quilt shops - has a thread count of 68 x 68 or more and is made with longer staple cotton thread. This makes it feel a little softer, accept dye better and have a longer life. It will still shrink a little in the wash, but not as much. PFD (prepared for dying) and batik fabrics can have up to a 200 thread count and generally don’t shrink at all." (http://quiltbug.com/Articles/choosing-fabric.htm)

So, where is the fabric identified as to the thread count?

I know-I've wondered this for years. Sure would make things easier.

I am not sure the manufacturers would ever accept a labeling system. They use very different "background" white goods for a wide variety of printing. Places like Moda even change over time or with different designs. I remember when Moda tried a very very thin brand of background cloth and got hammered with complaints. It frayed a lot.

The hardest part is to find out how many chemicals are added, for finishing the cloth for example. I am sure many of us have had good looking and feeling cloth turn into dishrags in the wash or shrink so much with a touch of steam that we wonder what will happen the first time it is washed whether solid or print.\

Now it is buyer beware.

I've used a variety of weights of fabric and not had a problem.

The problems have occurred if the fabric was one that frayed easily, not whether it was thicker or thinner.

The quilt I used as a teenager was a vintage DWR top (from the 20s or 30s that we had a local lady quilt for us. Many of the fabrics were what we would consider much too thin to use, but they were of denser thread count than the muslin centers and held up to regular use for 30-40 years. In fact it was mostly the muslin that was wearing out when I quit using it.

Not ALL solids are broadcloth. American Made Brand from Clothworks, for example, has a 78x74 weave, closer to quilting cottons and shirtings. Quality quilting cottons are generally 68 or more threads per inch (TPI), batiks range from 130x78 to over 200 TPI. When thread count gets too high, it's hard to needle.

Thread count isn't everything and can often be very deceiving. You have to know if they are counting the entire thread or the ply within the thread and what the yarn size is, for instance. Don't be a thread count snob, judge by the actual feel of the fabric, it's hand, and you'll do just fine. :)

Some "thin" cottons that are finely woven are VERY expensive. I bought cotton for baptismal gowns - It was $12.00/yard 50 years ago.