When filing for a Federal trademark, it's important to keep the SAM rule in mind.
SAM's not a person but a concept employed by the USPTO during their review process of new Federal trademark applications.
The USPTO will refuse registration "if the marks are similar and the goods and or services related." So basically marks do not need to be exact conflicts to be considered for refusal. ""Similarity in sound, appearance, or meaning may be sufficient to support a finding of likelihood of confusion," hence the SAM rule.
Let's take some time to dissect the second one – APPEARANCE
Similarities in appearance takes into consideration that consumers often see trademarks be it on television, on the web, magazines, etc. Because of that the USPTO will take into consideration marks that APPEAR to be similar to one another.
Let's look at an example to illustrate this point.
You have a cosmetics line that you plan to name Facing East & would like a Federal trademark. The comprehensive research you ordered showed a registered trademark for cosmetics for Facin' East. The spelling is slightly different but both marks APPEAR to be nearly identical.
*Comprehensive research will be on the lookout for SAM*