There are hundreds of trademark examining attorneys at the United States Patent and Trademark Office. Any one trademark examining attorney could be assigned to examine your application and could issue an initial "likelihood of confusion" refusal for your trademark application. Clients, of course, never see the "likelihood of confusion" issue in the same way as the trademark examining attorney does.
In order to attempt to defeat the refusal (which can be very challenging and ultimately unsuccessful), consider the Top Five relevant factors evaluated when making a likelihood of confusion determination:
1. Similarity/Dissimilarity of your mark and the mark(s) identified by the trademark examining attorney;
2. Similarity/Dissimilarity and nature of the goods/services (as described) of your mark and the mark(s) identified by the trademark examining attorney;
3. Similarity/Dissimilarity of trade channels in which the respective mark owners sell their goods/services;
4. Care/attention expected of the consumers of the goods/services of the respective marks;
5. Fame of the mark(s) cited by the trademark examining attorney.
Confused yourself now?
A trademark attorney can assist you in trademark selection so as to avoid wasting money on an application that could generate a "likelihood of confusion" refusal in the first place.