I have heard that in spanish, when people usually call each other by their names, they change the names according to their mood. For example, a person named Carlos can be referred to as Carlitos or Carlote by a person. Is it true that the way of pronouncing the name changes based on the person's mood? If so, is there any rule making these changes in the person's name depending on the mood?
Yes, it is true. I think it also depends on who you are addressing and how much confident you are with each other, since those name-modifications are usually used between friends, relatives or someone you are familiar with. For changing these names using some rules, you can refer to the "sufijos diminutivos" diminutive suffixes(e.g. Carlitos) in this link and to the "sufijos aumentativos" or augmentative suffixes.