As a current retail store employee, I can say, different places have different attitudes, and every employee is different. I can usually tell by looking at the customer whether or not they want any help by observing what they are looking at and how they are looking at it, but it is not always a sure bet. If it looks to me like they are just browsing and killing time, I may wait a few minutes before asking if they need help or until they ask me for help. If they look like they need/want help, I go directly to them. I am just not a fan of customers who get impatient when they have to wait a minute or two while I am helping someone else, especially when I get to them, and they just want to look at 50 different things and not buy anything.
Regardless, I think that you definitely experienced bad customer service from careless employees.
You must work at academy