[Phanx]

Enumerating regions is not really ideal... not only will it give you things that aren't fontstrings, but it'll give you all the fontstrings in the tooltip, even the ones that aren't in use. Here's a better way:

for i = 1, MyScanningTooltip:NumLines() do
    local left = _G["MyScanningTooltipTextLeft"..i]
    local text = left:GetText()
    if text and text ~= "" then
        -- do something with the text
    end
end

Also, when using the SetX methods (SetBagItem, SetItem, SetSpell, etc.) it's not necessary to use ClearLines; that happens automatically. The only reason to use ClearLines is to redraw the contents of an open tooltip without reopening it, and I can't really think of any good use-cases for doing that either.