Nowadays it is all too common for machine and embroidery thread to appear to come from major companies,whilst being much inferior. Price is usually a good indication,but not always,as some countries have much lower costs of labour but access to good quality raw materials.

The obvious thing to do is to try a single reel or skein from a supplier who is new to you. To buy a full range,even at a ridiculously low price,is foolhardy! Some sewing thread is "tender",and sold totally on price-but useless. The large assortments sold in bargain shops are examples.

With embroidery threads,apart from the quality of the actual fibre,colourfastness is paramount. Much embroidery work never gets washed or drycleaned,but do you really want to put in weeks of work on a washable item only to end up with a streaky mess?  So much better to try a single reel on a piece of waste cloth,and subject it to the conditions that the finished work will receive.