What is the word for a sentence that initially sounds profound or deep, that is, in fact, meaningless or empty?

Solution 1:

Possibly platitude:

A trite or banal remark or statement, especially one expressed as if it were original or significant.

Solution 2:

Perhaps grandiloquence

Pompous or extravagant in language, style, or manner, especially in a way that is intended to impress: a grandiloquent celebration of Spanish glory

Similarly, bombast

High-sounding language with little meaning, used to impress people.

[both Oxford Dictionaries Online]

Solution 3:

I good word for this might be meretricious, which means, courtesy of Oxford:

Apparently attractive but having in reality no value or integrity.

It's not exactly what you're looking for, but it describes pretty accurately.

Solution 4:

Were you perhaps thinking of deepity?

The term refers to a statement that is apparently profound but actually asserts a triviality on one level and something meaningless on another.

E.g.: "love is just a word"

On one level the statement is perfectly true (i.e., love is a word) but the deeper meaning of the phrase is false; love is many things — a feeling, an emotion, a condition — and not simply a word.

Solution 5:

If done intentionally then I might say sophistry, which the OED defines as:

a. Specious but fallacious reasoning; employment of arguments which are intentionally deceptive.

In offices it's also quite common to refer to what you describe using an impolite term for bull excrement.