Samples
Designers and brands are always looking for new factories to produce their products, as they continually look for ways to maintain quality and keep costs down. Hence they will ask factories to make a sample set of garments to prove not just their ability to do the design, but to get it right in bulk on a production line scale.
Naturally sometimes these samples are unsuccessful in that the designer rejects the offer of the factory, in which case the factory has a large batch of garments with no customer for them.
These are what are sold as samples. Sometimes it is just individual items, but more often a factory will have a small set, such as a dozen, but these sell out fast when they end up in on of the factory outlets along Granville Road as they are very desirable.
Of course they actually may have failed the quality control of the designer, so in this sense they are similar to rejects, but often times the failing is so minor that it would not concern the normal buyer. And in many cases the failure of the business deal between the factory and the designer may be due to other commercial issues such as payment terms or credit, rather than the quality of the garments themselves.