I know you are looking for primarily DT member opinions from the sounds of it, but if you're interested in my 2-cents then here it is. I think we should be conservative with tagging users that are in similar situations to this. If you cannot be extensively positive that merit trading was taking place, then you probably shouldn't leave a negative rating. A neutral rating for your suspicions might be appropriate, and if the trend continues then a negative may be in order. It would seem that as lower ranking members are attempting to understand the merit system better they are inevitably going to give one another merit in a similar fashion to this. Being on the fence, I would lean towards the side of "caution" and not tag this user. It is such a small amount, as you said the posts were somewhat decent and it doesn't seem as egregious or obvious as I would like it to be in order for them to receive a negative rating.