There are numerous ways to test what is going on here. Work through your CSS's classes in FireBug and enable and disable styles until you get a result your expecting. There is obviously some style declaration error some where that is causing this particular style to fail. Because you are right, inline styles take priority over external style sheets, and over parent styles. Since you know this focus on the table area of your HTML and see if there are any syntax errors, scripts that are overriding the value, etc.
Also test different text styles for this "td" tag to see if other styles work, such as:
color: blue;
line-height: 10px;
letter-spacing: 5px;
Also note that text-align:left
is a default value if the direction property is "ltr" (left to right) which is default. So it could be possible that some of your styles for this HTML table element are not being applied.