“Good lenses, bad frames” is used to describe someone who gives a bad firstimpression but is actually a good person, or someone who doesn't appear to becompetent, yet is extremely capable at what he/she does.
“Good lenses, badframes” (直译为“好镜片，赖镜框”) 通常用来描述那些给人第一印象不太好，但实际上人品很好的人;或者看起来没什么本事，但其实工作能力很强的人。所以，可以译为“人不可貌相”或者“真人不露相”。
For example:
Dr. Bruce is a spaz, but he's one of the best doctors I know. You wouldn'tknow it by looking at him...good lenses, bad frames.
布鲁斯医生是个怪人，不过他是我认识的医生中最好的一位。看他的样子你是看不出来的，他是真人不露相。