Smooth is a starting point
A raised wall texture reduces continuous adhesive contact and may show through a thin covering. Check flatness, paint adhesion and surface cleanliness. Do not describe a textured wall as suitable without a trial of the proposed wallpaper on that wall.
Distinguish repeat from seam method
Pattern repeat describes where the artwork aligns; seam method describes how adjacent edges meet. Request both. Use matching references and check the batch before cutting an entire order. Keep the repeat measurement with the design code when planning the cuts.
Keep a useful trial record
Photograph the wall and retain the sample code. Note paint type, preparation and installation conditions. For a trade enquiry, include the proposed roll width, quantity by design and any concern about the existing finish.