When sourcing slub yarn printed fabric, the most critical feature is the textural consistency of the slubs. You should ensure the 'thick and thin' effect is intentional and not a result of poor spinning. Look for a uniform distribution of slubs to prevent 'barring' effects. Additionally, verify the fabric weight (GSM); for apparel, 120-180 GSM is standard, while home textiles may require >200 GSM. The printing precision is also vital—ensure there is no pattern bleeding or misalignment, especially on the uneven surface created by the slub texture.