Hi Christiana!   Sometimes it's very hard to see extensions if there done right and human hair is used.  Things to looks for would be hair that doesn't move on the back of the scalp.  That is because it's glued on!  Sometimes you can see if it's sewn in, partically with braids. Once, while working in the cosmetic trade, I saw the worst extenison job ever.  A lady came up to the counter and her extention layer was at her scalp line and it was coming off!  At first I thought it was a wig but it was not.   Hope this helps!