Pre-Press Graphics Designer Question:

When a graphic designer has a page of their portfolio website dedicated to testimonials or keeps an offline copy of positive reviews they've received from past clients, it tells you their customers are happy with their results and willing to publicly vouch for them. If they don’t offer to share, just ask.

However, if they’re unable to produce a few positive testimonials, that’s might be an indication they are unable to sustain good client relationships or produce quality results. Tread lightly.