Of course, I have "experience" to back up my comments -
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Is it shedding "dust"? It probably has a lot of sizing and will be limp after it is washed.
Is the pattern printed "on-grain"? If it is printed off-grain, no amount of stretching or blocking will get it to be printed on-grain. (Sometimes the fabric is pulled crooked when it it is being put on the boards, but I look at the back to check to see if it is "straight" - or straight enough.
I try very hard to buy fabric that is printed straight and looks on-grain while still on the bolt.
Do not believe a clerk/associate when she says it will straighten out when it is washed. Sometimes it does - sometimes it does not.
Do your fingers turn color when you handle it? Leave it in the store.
Does it feel "icky"? Leave it in the store.
Does it rumple easily? I try to "crush" a handful of the fabric to see if it is relatively wrinkle resistant.
If I truly like the fabric and have not seen it before - get it while it is available - even if it is not on sale.
Is the piece big enough for what you want to do with it? I tend to be skeptical about finding more later.
What is the return policy if the fabric is a bleeder? If one is a washer - and I am - save the receipts and wash the fabric within a week or two of bringing it home.
I had some black that I purchased years ago - and it shredded - yes, shredded - in the washing machine and left "soot" all over the place. Odd - the two blues that were from the same time frame and same brand name washed up beautifully.
Now - if a fabric does not pass my washing and drying phase - out it goes into the trash. I will not donate it for someone else to deal with. If it is not stable enough for me to use - I think it is a dirty trick to dump it on someone else.