Many entrepreneurs believe all money is created equal. As long as somebody recognizes their million dollar idea and writes them a check, the source really doesn’t matter. Most angel investors are pure, but there are some exceptions to watch out for:

1. Shark angels. This is the ultimate bad guy whose sole intention of getting involved in early-stage investing is to take advantage of what they believe is the entrepreneur’s lack of financial and deal-making experience. If the term sheet process turns to pure torture, it may be time to respectfully bow out.

2. Litigious angels. The litigious investor will look for almost any excuse to take you to court. This type of investor never really focuses on the returns your company can deliver, but instead tries to make money by intimidation, threats and lawsuits. They know you won’t have the resources to fight them, so they count on you “caving.” Keep your attorney close by your side.

3. Superior angels. A number of successful business people, some of whom become angels, develop the belief that they are destined for greatness because of their clear superiority over everyone else. These are usually overbearing, negative people who are hypercritical of every decision you make. Don’t be intimidated into bad decisions.

4. Control freak angels. This angel starts out looking like your new best friend. Once you are funded, he waits until you hit your first pothole and then points out “gotcha” clauses in your agreement that give him more control. This escalates into a requirement that he must step in to run your company himself. Only your Board can save you here.

5. Tutorial angels. The tutorial investor is not after control, but wants to hold your hand on every issue. The mentoring offer always sounds good up front. But after they write the check, it soon becomes apparent that their desire to be helpful 24 hours a day is a nuisance at best. Initially, your gratitude for their investment may prompt tolerance, but eventually the burden wears you down. Keeping your distance is the best solution.

6. Has-been angels. These tend to appear with every perturbation in the economy. They are usually high-flyers with a liquidity problem. They are still at the country club every day, but are now running up a tab. They will meet with you, and ask a thousand questions, but never get around to closing the deal. Learn to ask the closing questions.

7. Dumb angels. Wealth is not synonymous with business savvy. You can spot dumb angels by the questions they ask (or don’t ask). If they ask superficial questions or don’t understand business, a successful long-term relationship is not likely. But don’t forget that people with wealth usually may have some savvy friends to meet.

8. Brokers posing as angels. These people are all over the place, often posing as lawyers and accountants. They have little intent to invest in your company, and will eventually solicit you to sign a fee agreement to pay them to introduce you to actual investors. Brokers are often worth the fee, but don’t be misled about who is the angel.

How do you avoid most of these? Whenever possible, only accept investments from individuals in credible, professional angel investing organizations – not people who solicit you. Even then, do your own due diligence in the business community. Ask what other companies they’ve invested in, and talk to the CEOs of those companies to find out what kind of investor they’ve been.

Also, make sure your lawyer writes the initial investment document or term sheet – not the investor. This document should be standard for all your investors and not negotiated on a one-on-one basis. Watch out for any attempts to add clauses that can come back to bite you. Not all angels these days are even trying to earn their wings.

Marty Zwilling is CEO & Founder of Startup Professionals Inc.