In Good Adwords, why is it recommended that you delete poorly performing keywords? In my view they could be considered niche words which though are searched for very little, may bring good conversions. Is that not the case? Is there any harm in keeping them there?
if they are poor performing ie impressions but few clicks which = low ctr then your overall ctr for that ad group will be lowered which in turn decreases relevance pushing up your cpc and/or lowering your ad position. you should always get rid of your poor performers. maybe start a new ad group with them based around a more relevant few keywords and write your ad to include these keywords. each group of keywords should be tightly bunched around the same word. this makes it easy to write a good relevant ad which should ALWAYS include your keyword theme.
simple - relevance, CTR, CPC etc aside, if you have two keywords, keyword 1 converts at £2 per sale, keyword 2 at £10 per sale. For every £10 spend on keyword 2, keyword 1 could be making 5 sales rather than 1.
i think what your missing is that a poor performing keyword - isnt a poorly searched for keyword. if a keyword is only getting 1 or 2 clicks, of a handfull of searches, and its your cheapest keyword (cause its so specific) then it might be a very good performer, you measure the performance of keywords not based on clicks or searches but conversions to your end goal - sales.
mmh. To clarify or deminstrate what you mean, could you advise based on the following quick report which I have compiled (See Image attached), stating your recommendation?