When you are going to go out and go fabric shopping then there are several ways to think about doing it. You could order some samples right to your very own home and look at them there. Once you decide on what it is that you want then you could place your order for more, ordering bigger amounts of the fabric you are looking for. But that is not the only way to do the fabric shopping that you need to do. You could also go in person to the store and see the fabric on your own as well. This way you can get to really see the detail of the pieces and it gives more of an honest look at the fabrics that you might be considering.
Not everyone is going to have the time though to check in at the store and see the fabric that they have. Also, if you are just looking for a basic print then it can be easier to shop for that online because there likely won’t be much change in how it looks. The photo and in person should look quite similar. But that might not be the case if you have a more detailed fabric, it might look different in the light for example, or the detailing might be different than you pictured it online.
For these reasons it pays to consider multiple options when looking for fabrics and doing your fabric shopping. Ultimately it depends on what you are looking for. For something simple it might not hurt to just buy it online and take your chances. But if you are spending more money on that fabric then you will want to know you are getting the right thing that you want. That can come with testing it out and getting those samples.